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See also:

Subsections on this page:

About Postdates - About Being "Overdue"

Problems and Hazards of Induction in Labor - a handout from The Coalition for Improving Maternity Services (CIMS)

Post-Term Delivery Raises Risk of Complications, Illness for Newborns [1/19/16] - Post-term deliveries, even among low-risk pregnancies, are associated with increased short-term risks to newborns, including illnesses and infections, which land them twice as frequently in the neonatal intensive care units (NICUs).

[Ed: This has to do with the age-old problem that we have no way of knowing a given baby's ideal gestation length.  Even if we know the exact moment that conception occurred and when implantation occurred, we have no way of knowing this baby's innate rate of growth.  So we cannot know whether this baby will be healthiest born at 37 weeks or 44 weeks.  Yes, after the baby is born, we can look at the details of the baby's development and do a fairly accurate gestational age assessment, but we can't know until we see the baby.  Some very skilled midwives say they can do a vaginal exam and palpate the baby's skull plates through the lower uterine segment to assess how hard the skull plates have become; this helps to assess the baby's readiness to be born and answers the question of whether the head is hardening to the point where it won't mold to fit through the pelvis.  But it's a very rare skill.

So, what's a conscientious mother to do?  My personal recommendation is to help prepare your body to go into labor as soon as baby throws the switch.  Sometimes, when babies come late, we can do a gestational age assessment and see from the physical exam that the babies are truly postdates.  Why does this happen? Sometimes the mother suffers an emotional shock, or there can be family visiting that keeps a mother from relaxing enough to go into labor.  More often, I think it's that elevated fasting and postprandial blood sugar levels have prevented the uterus from becoming receptive to oxytocin and toning itself as a muscle.  Sometimes, for an older mother who is having a first baby, the cervix has toughened up with age so the normal early labor process takes quite a number of days to trigger labor.]

Exclusive Q&A with Rebecca Dekker – What Does the Evidence Say about Induction for Going Past your Due Date? [4/15/15] by Sharon Muza

The Evidence on Due Dates by Rebecca Dekker, PhD, RN, APRN - this is an excellent, well-researched article.  I would have liked to see a discussion about genetic variation of due dates, i.e. Asian vs. Scandinavian/Germanic, and the fact that gestational age assessment shows that there are a number of reasons why babies are born later than their genetics would have liked.  In my experience, the main reason for this is elevated glucose levels during the last half of pregnancy.  Some would call this sub-clinical gestational diabetes.

The concept of being "over due" is a strange one, as it mostly ignores the inevitable variations of normal that are inherent in any biological system.

Do you expect to have the exact same biological rhythms as all your friends?  Do you like to eat and sleep at the exact same times?  Do you expect your baby to roll over, sit, crawl, and walk exactly on schedule?  No, we all understand that there is tremendous variability in the timing of these developmental milestones.  Similarly, different babies have different gestational schedules.

Women receiving assembly line care can expect to be treated as an identical cog in the obstetric machinery, without regard to individual variations, and then you need to be thinking about ways to prepare your body to birth in a timely fashion.  (Even if it's too late to do this for yourself, think about this for your sisters, cousins and nieces if your family has a tendency to "go late".)

Personally, in my practice, I consider the ethnic variations in pregnancy length, the individual histories regarding gestation, and the clinical signs as pregnancy progresses.  Sometimes, you really do need to be worried about going too long past "the due date", but it seems like better care to be determining this on a case by case basis.

What’s a Poor Midwife To Do? - Gloria Lemay editorializes on the subject of midwifery care ending at 42 weeks

Recommendations from Lamaze - Induction

Routine Induction of Labor at 41 Weeks' Gestation Not Recommended [Medscape registration is free] - Currently, the American College of Obstetricians and Gynecologists recommends labor induction at 42 weeks' gestation in women with favorable delivery characteristics. Based on their new findings, the authors conclude that there is not sufficient evidence to change this recommendation to 41 weeks.

Forty weeks and beyond: pregnancy outcomes by week of gestation.
Alexander JM, McIntire DD, Leveno KJ
Obstet Gynecol 2000 Aug;96(2):291-4

While poking around PubMed to see if I could find an abstract for the above article, I was surprised to see that a review of Cochrane database seems to support induction at 41 wks.  Any comments.

That's what it says. If you compare inducing at 41 weeks with a "policy of waiting"  then the outcome is better .... less cases of fetal distress or stillbirth in labor (no effect on IUFD).  It is really hard to find data on women carefully monitored with some "cut off" period --- It seems that an all or nothing (induce now, or just wait)  approach was taken.

But..... there are few people who would advocate a "policy of waiting" which did not include monitoring and intervention when appropriate, or induction at SOME point if pregnancy still continued.

I think "post-dates" is a continuum. A certain portion of babies become at risk at some point in pregnancy and this rate rises as time goes on.  A 41 week baby obviously does not have the same risk as a 44 week baby, but they are both lumped in the same category.

Good data about closely monitored post-dates pregnancy is very hard to find.

Both extremes seem weak to me -- inducing all at 41 weeks or not inducing ANYONE ever....

Detailed Paper about PostDates

Faith Gibson's Homebirth Consent Form for Macrosomia & Post-Dates in Multip

A summary of what the Guide to Effective Care in Pregnancy and Childbirth (2nd ed.) has to say about postdates:

The rate of post-term (greater than 42 weeks) varies from 4-14%.....much dispute about what exactly is meant by a post-term pregnancy (i.e. 41 weeks vs. 42 or 43). Post Maturity refers to an infant with loss of subq fat, dry cracked skin, meconium staining and may include asphyxia, respiratory distress, convulsions, and death....Perinatal mortality is increased in post-term pregnancies. Some of this increase is due to congenital malformations which are more frequent in post-term pregnancies (i.e. anencephalics-sam). The incidence of neonatal seizures, a marker of perinatal asphyxia, is between two and five times higher in infants born after 41 weeks.....

Elective delivery, either at term or at 41+ weeks, reduces the risk of meconium stained fluid... A policy of elective induction at or beyond term has been shown to result in a decrease in perinatal deaths not due to lethal anomalies.....The improved perinatal mortality appears to be confined to induction at and after 41 weeks. There is no evidence of a beneficial effect of induction at 39-40 weeks gestation....

Active induction policies are not associated with an increased use of cesarean delivery; indeed trials show a small but statistically significant decrease in cesareans in induced labors at or beyond term.....This unexpected finding may reflect characteristics of the women participating in the trials (i.e. cervical ripeness) and the methods used for induction......

A single trial of breast stimulation and sexual intercourse for women from 39 weeks to delivery showed a decrease in the incidence of post-term pregnancies. Sweeping the membranes may also reduce the likelihood of the pregnancy proceeding beyond 42 weeks.....

Induction of labor at less than 41 weeks is not associated with any advantage apart from a small reduction in meconium staining. The reduction in perinatal death seems to be confined to pregnancies 41+ weeks. A policy of routine induction at 40-41 weeks in normal pregnancies cannot be justified in light of the evidence from controlled trials, and is unacceptable to many mothers. Induction of labor after 41+ weeks is not associated with any major disadvantage and reduces the risk of perinatal death. Provided that appropriate induction methods are used, it may also result in a small reduction in the high risk of cesarean section run by women with post-term pregnancies. In light of the available evidence, the best policy is to offer women a choice of induction of labor by the best method available once the pregnancy has with certainty reached 41 weeks or more.

There's apparently a clinical way of predicting when a mare is close to giving birth - Predict-A-Foal - if we had something like this, we might do a better job of knowing when women have really gone past the time their body is meant to give birth.  If nothing else, the human analogue - Predict-A-Baby - would make it much easier for midwives to plan their lives!

Sr. Angela Murdaugh says we see so many moms going past 42 weeks because we calculate the due date in a way that sets up too many women to go overdue! Traditionally we calculate using Naegele's Rule, which was postulated in 1805 and studies have shown the average well-nourished primip goes 10 days beyond that, and a multip goes 5 days beyond that. She advises calculating using Nichols' Rule, which was written up a few years back in the Journal of Nurse-Midwifery. I don't remember all the details of how to calculate using it, but she said if nothing else, add 5 days onto the Naegele's Rule EDD. Since I've been doing that I am MUCH closer to actual delivery dates and I delight in telling women 'See, I told you it would be around this date' when a doctor has given them an earlier EDD. Since Nichols' Rule was written up in a professional journal it is accepted as a standard of care.

I am very interested in the issue of what constitutes "over-due" or "post due dates". Sr. Angela Murdaugh recommends using Nichols' Rule rather than the Naegele's Rule most often used (developed in 1805). This is because Nichols' Rule is much more accurate since the majority of well-nourished women will go past the due date that is assigned per Naegele's Rule and not suffer any bad consequences. In fact she cites studies showing the average primip goes 10 days past the Naegele's Rule EDD. As we know we're seeing a plethora of induced labors within a week of the EDD and the babies do not often appear postmature.

As a mother whose babies were all "overdue" I really resent this assumption that the mother is holding on to her pregnancy or has some emotional problem that needs fixing. Isn't this playing amateur psychiatrist? Maybe my babies just thought that the food was good and rent was free so they wanted to stay??? I would have done anything to start my labor! Castor oil didn't work but I sure got a thorough cleanse, herbs didn't work, no traditional midwife trick I'd read worked, and I'd cry every day I woke up and wasn't in labor. My grandmother went 2-4 weeks post-dates, my mother went 2-3 weeks post-dates, and I've done the same. My periods weren't extra far apart, they average 28-30 days apart. Not one newborn showed signs of clinical post-maturity, all the placentas were nice and healthy. My last baby weighed nearly 10 and 1/2 pounds and was induced via acupuncture at 13 days post-dates, or else she might have been 3 weeks over due like her siblings.

My five kids were all from 7 days to 2 1/2 wks past my "due" date. I imagine most of the women midwives see eat super-nutritiously compared to the days when these men's "rules" were established. A lot of babies today are staying in longer because they are getting everything they need on the inside. Ina May says all she does to keep moms of twins from delivering early is feed them, feed them, feed them.

I think there is a great difference between postdates and postterm Term is + or - two weeks of the EDC. So postterm would be after the 42 second week is complete. Thus 42.1 Postdates is another matter entirely. It would be 40.1 Am I correct in my definition of these words?

I really don't like the new way of denoting weeks. If a woman is supposed to measure cm for week, when you use the new terminology she doesn't. So if she is 30.2 then she should really measure 31. My regs say if size is 3 cm more than her dates she has to see a doc. So now you run into a semantics problem. If she is 30.1 and measures 33, the numbers look she is off. I like saying in the 31st week instead of 30.1 What say you all?

As I understand the terms, postterm is a post delivery diagnosis based on a Dubowitz (or other newborn assessment) that places the baby at greater than 42 weeks gestation. That wizened old man look with little vernix, little lanugo, heavily wrinkled, etc. Postdates is the terms used prior to delivery referring to a pregnancy that is assumed to have gone beyond 42 weeks of gestation. Because of the fluidity of even the best dating criteria, a pregnancy that is "postdates" may produce an infant that assesses at term. In other words, "postterm" is a diagnosis of a newborn condition, while postdates is a diagnosis of a pregnancy condition. We can never "know" if a fetus is postterm until it is delivered.

At my birth center, we encourage sex, walking, breast stimulation, and (finally) castor oil (with some black and blue cohosh thrown in for good measure) and membrane sweeping. We almost never have to send anyone to the hospital for induction because they reached 42 weeks (our protocol). We put great emphasis on establishing an accurate gestational age at the first visit. We rarely do early sonograms (or any sonograms, for that matter) but will for unsure dates. We are lucky to have a population of educated women who are aware of their bodies and are usually active attempting conception, so their recollection of LMP and probably conception is usually pretty accurate.

I'm really curious now about everyone else's rate of >42 weekers. And whether you always try induction just before 42 weeks, and if your protocols require transport at 42 weeks. It's one thing to look at statistics of "failed home inductions" and another to see how many naturally go past 42 weeks.

I have just finished our 1995 stats (I know, I know....I'm a little slow, but I do all the data and we had 479 women (with 487 babies...6 sets of twins, 2 sets of triplets) that year. 217 primips. :(

Of these 479 women:

140 (29.2%) delivered between 40-41 weeks 105 (21.9%) delivered between 41-42 weeks 27 (5.6%) delivered between 42-43 weeks 1 went >43 completed weeks

And this is in a practice where some of the docs want to induce routinely at 42 weeks. We continue to fight this practice, but do careful testing and AF checks after 41 weeks.

75% of my clientele go in the 41st week.

I cannot go past the 42nd week by protocol. Thus we do a three day induction plan with cohosh at 41.2 or 3.

"Husband-Coached Childbirth"
by Robert A. Bradley, M.D.
Fourth Edition
Revised and edited with Marjie and Jay Hathaway, AAHCC
Chapter 10: "When Will the Baby Come?"

"Average gestation is now known to be 41 1/7 weeks, not 40 weeks as previously thought. (Mittendorf, et al., "The Length of Uncomplicated Human Gestation," "Obstetrics and Gynecology," vol. 75, no. 6, June 1990.)"...

"God schedules a birthday, not man."

Girl Twin May Determine Pregnancy Length

This seems somewhat odd because the common wisdom among midwives is that girls come earlier than boys.  (I think this is supported by the research but don't have references hand.  Maybe girls somehow "normalize" length of pregnancy, and since twins tend to come early, the normalization in that case is to extend the pregnancy, whereas in a singleton pregnancy, normalization is to come slightly earlier.)

I am finding it a bit hard to track down specific information on why it is supposed to be a problem to go more than 14 days 'overdue' - does anyone know what exactly might be a problem, or more of a risk? I would be so grateful for any information or experiences - I am still hanging on for a homebirth, but would feel much more confident about doing so if I knew more.

In my opinion, some babies just take longer to "cook" than others. First, I am assuming that your midwife, and you are very sure about your dates. If so, and you are definitely "post-dates", then what the risk is called is "post-mature, post-term, post-dates syndrome" in which the placenta seems to be the potential problem. If you have undergone a Biophysical Profile, or placentography, your placenta may of been "graded" according to a scale of 0-3, rating its maturity level. The main risks for post dates pregnancy have to do with increased size of the baby thus more difficult delivery, and the ability of the placenta to withstand the "stress" of labor. What I mean by stress is, the placenta, during a contraction has a reserve amount of 02 for the baby, in a very old placenta, the supposed risk could be less 02 to the baby, resulting in heart decelerations during labor, with fetal distress being the end result. (your midwife will be monitoring your baby, so she would hear this if it happened, and take appropriate action) Another possible risk is that the placenta is so aged, that the transfer of nutrients and 02 to the fetus, through the placenta, may not be very good even before labor and the fetus then begins to lose weight, and have a decreased amount of 02, resulting in a variety of problems depending on the severity. This is due to what is called "Placental Insufficiency". This of course it the worst case scenario, and because you have been having non-stress tests, and other fetal-well being tests, it sounds like this is ruled out, in your case.

According to "Human Labor and Birth" Oxorn and Foote (a standard medical text) :

" While prolongation of pregnancy beyond 42 weeks may have an adverse effect on neonatal outcome in some cases, fetal death is rare. Induction of labor does not improve the results. What the latter practice does achieve is an increase in the rate of cesarean section because of failed induction. An uncomplicated postterm pregnancy is not an indication for the induction of labor. Early delivery is necessary only when tests of fetal health show that deterioration is taking place." page 712

So sit back, relax, drink Red Raspberry Leaf tea, make love to your husband often (prostaglandins in sperm soften and ready the cervix for dilation), and enjoy your time alone until your baby comes.

Ob.Gyn. News Vol. 21 No. 14, July 15-31, 1986
"How to Distinguish True Postmaturity from 'Benign Postdatism'"

"Appropriate management of a post-term pregnancy requires the ability to distinguish 'benign postdatism' and true postmaturity, Dr. Robert Resnick said at the annual Orange County ob.gyn.congress....

"Gestational age is in most situations only a good estimate at best....

"Biparietal diameter obtained ultrasonographically, the date of first recorded fetal heart tones, and data from early pelvic exams can help pinpoint the gestational age....

"Induction of labor usually is indicated at 42 weeks.

"If labor cannot be induced, the combination of twice weekly reactive nonstress testing and estimation of amniotic fluid volume provide the best means of monitoring the fetus.

"In patients who carry beyond 44 weeks' gestation, termination of the pregnancy needs to be given strong consideration, Dr. Resnick advised at the Costa Rista meeting."

NO implicated in post-term labor
Source: Obstetrics & Gynecology 2004; 103: 657-62

Postdates Protocols

Our local standard of care is to get an NST followed by AFI at 41 weeks (if NST is not reassuring, the AFI is bumped up to a BPP), repeat NST in 3-4 days, and induction at 42 weeks.  We consider AFI 5 or greater as OK. Anything less, or a bad BPP, buys the mom an induction that day. [4/06]

Apr., 2006 - it seems like many places have completely stopped doing placental grading.  They're considered passe, not contributing valid information, etc.

Assessing Fetal Well Being

Auditory evoked response of the human fetus: simplified methodology.
Luz NP
J Perinat Med 1991;19(3):177-183

A test was considered positive when sound stimulation evoked no movements or only a slight, slow, not immediate movement was observed by the mother or the professional applying the test. A test was considered negative (fetus in good health) when a fetal immediate sudden, strong, Moro like reaction was observed clinically (startle reflex). This test produced a sensitivity of 57.35%, greater than any other observed in nonstress cardiotocography.

I give a Fetal Movement Chart at 40 weeks (or sooner if I get spooked); I do weekly NSTs also. I encourage labor and follow my instincts like you said. An ultrasound scan if it looks like we might have to transfer care or if other concerns.

I think there are a lot of midwives who feel the 42 week cut off isn't fair especially for ladies who routinely go overdue probably because they have long cycles and actually ovulated later than the time allowed for in Naegele's Rule. I've heard there have been studies that show that women in colder climates are pregnant on an average longer than women in warmer climates. I don't know who or where published, but I don't care enough about it to research it. I do know that being down here in Texas, my clients usually deliver between 40 and 41 weeks. I have only had two clients go to 42 weeks in the past 5 years.

Aren't late sonograms also good for checking the placenta as well as the fluid volume? I mean, I hadn't really thought about the risk of IUGR, mostly I guess because the babies I catch are usually between 7-9 lbs, so I will take your words to heart. But if a woman is getting close to her 42 week, (41 plus 7 days) and if the fluid levels are OK and the baby is reactive and has good variability in the heart rate - that is the case I would think a back-up sonogram would be helpful in deciding to wait a few more days for labor. Your alternative is induction, loss of a home birth. Of course, the ultimate goal is healthy baby and healthy mom - no matter what. It's a difficult situation to be in and with the medical establishment doing routine inductions on or about due dates now, we barely have a leg to stand on.

I base my decisions on many things - menstrual history, past pregnancy history, current pregnancy progress, maternal instincts, midwife instincts, and medical tests and consultations as they may be called for.

I do like to see an ultrasound when they get to 41 weeks.

We let our moms go 14 days. We encourage kick counts and sometimes send them in for NST. We usually find that mom is holding the baby back for some reason so we do some gentle counseling around 10 days. Sometimes dates are just off.

I let my primips go 42 weeks and multips 43 weeks. I tell them this is not engraved in stone but I get nervous outside of these parameters. I am also more relaxed and flexible if a woman always goes postdates (like me 42, 41.5, 41.5, 41.5 - all healthy). I did have one primip lose her baby at 41 weeks (placenta gave out). We delivered her in the hospital (my blessed husband stayed in the car with our 3 week old so I could run out and nurse). My back up OB said this is why many docs induce at 40 weeks. I do suggest an ultrasound at 41 weeks on primips to check for oligo. But mainly I have my moms start walking at 34 weeks 20 to 30 min...helps a lot. And I have a whole slew of things to help get a mom going...EPO, stripping membranes, herbs, sex, long talks with mom and dad (just checking), prostaglandin gel, castor oil, acupuncture, homeopathics...

Our standards say we can't do moms after 42 weeks, so we usually try to nudge them when they start heading in that direction.

Anyone know whether there is any good research basis for scanning all low risk women at 41 weeks?

I never did 41 week ultrasounds and still don't routinely but I defiantly consider them due to a fetal death in a primip at 41 weeks. She came in for her 41 week prenatal and no heart rate... baby died from placental insufficiency..it went past the 75% mark ( the placenta will continue to support life until more than 75 % is gone). Beautiful baby girl. My backup, who will let women go more than 41 weeks said this is why so many OB's are inducing at 40 weeks and it seems prudent to do 41 week biophysicals.

I have had five client's with IUFD's at <<40 weeks, one at about 36 weeks and one at 37 weeks and 3 at about 20 weeks...somehow I have escaped being touched by IUFD at postdates and I thank God often for that. So if I was to have your same fear, I would have to start doing weekly ultrasounds on everyone over 18 weeks!

I understand the fear that sometimes surrounds the practice of midwifery and obstetrics.....after all we want EVERY woman to have the perfect pregnancy, the perfect birth and the perfect baby....no less (or loss) is acceptable. But we have to remember that no matter what level our technology, there will be dead babies, dead mothers, c/s, etc.

The real questions here are: Does it really help to do post-dates ultrasounds? Will ultrasounds always show a baby about to die? If the ultrasound shows a baby in dire distress, will it even survive labor? What about all the other possible causes of eminent death that can't be seen by a normal ultrasound?

In our area there are many levels of ultrasound available. We have a Fetal Assessment Center that can do many ultrasound related tests on the fetus and placenta to determine fetal well being. They are very expensive (>$200). But even though this place does nothing but these fetal assessments, they are not perfect....for example I had a client at 42 weeks go for an assessment. The report said that the baby was in good shape, and that her dates were off and she was really only 38-40 weeks, and that there was vernix in the water and baby was small. The very next day my client went into labor (on her own) and out came a very well-done, 8 lb. baby with tons of particulate meconium in the water, not a bit of vernix.

We have to remember that ultrasound is not a perfect test and that even though we appear to be seeing the baby and placenta, we are only seeing a computer generated image of sound waves bouncing off the baby and placenta, and many things can render those images incorrectly. The ultrasound is only as good as the equipment, the technician and the person reading and reporting the results.

Having a client loose a baby is about the worst thing we can imagine, but I feel we, as midwives, have to continue to be the advocate for non-intervention when at all possible....it is mostly because of fear that doctors want to control pregnancy and childbirth.....and we all know that our stats are better, so why would be try to emulate a profession with worst outcomes?????

I do not have this fear you speak of and do not do routine ultrasounds in any of my clients. However, if someone goes postdates I do have this in the back of my mind...it really depends on where the couple is at and what they want. I like to keep my clients very informed of all their choices and the pros and cons of all tests, etc.

Induction at 41 weeks is exactly what I recommend. Based on the Canadian study ( and others ) induction at 41 weeks is cost-effective and not associated with adverse outcome - au contraire it prevents stillbirths.

I think I have to take issue with this one. The Hannah study and the CCPC meta-analysis have both stated that this appears to be a trend (again the problems of trying to achieve significance with an event that occurs in small numbers). But the interesting thing to me is that in Mary Hannah's study, one of the 2 fetal deaths was in an post-dates infant that weighed 2600 gm...was this death due to post-datism or secondary to IUGR? The other was in a woman who had no surveillance after trial entry other than fetal movement counting and then had a fetal demise.

The meta-analysis includes 2 deaths that occurred in a study published in 1969, prior to the time when the fetal surveillance methods (or U/S for accurate dating) were available. It's inclusion in the meta-analysis considerably skews the numbers...there were only 7 deaths in total in the "expectant" management group in the meta-analysis.

Actually, it's not placental grading that bugs me, but amniotic fluid volume estimates. One of my family doc friends once commented to me that he sees an awful lot of AF splashing around with these births in which there's supposed to be oligohydramnios. I personally recently had the pleasure of a resident getting absolutely soaked from head to toe during a breech birth in which there was supposed to be "relative oligohydramnios" (whatever that means).

I don't debate that true reduction in AF is a bad thing, but I think some of these guys may have a heavy hand with the transducer. Then women end up getting induced at 41 because of low amounts of fluid, when, in fact, there's lots.

I confess that I have based my comments and my current practice on the original Hannah study (and the parallel economic appraisal). I haven't yet had a chance to look up the CCPC and Hannah meta-analyses. Perhaps you could post them to the group if you have ready access.

Induction of Labor as Compared with Serial Antenatal Monitoring in Post-Term Pregnancy (1992)
Hannah ME, Hannah WJ, Hellmann MB, et al.

A while back one of my midwife friends sent a woman with PROM in for a biophysical profile at a very reputable u/s center. The BPP came back 0 (zero). By the time the results were made available to her the woman had begun labor but because of the results, only, she immediately sent the woman into the hospital. The hospital couldn't understand the results of the BPP, except of course the reduced AFI, because of the ROM. The baby never showed a single hint of distress and the woman went on to have a normal delivery of a vigorous baby.

Makes you wonder about these tests!

A biophysical profile (or part of it - i.e.., liquor volume & CTG) might be appropriate AFTER 42 weeks. I recently did this twice weekly in a woman who wanted to go post-42 weeks for a VBAC attempt after three previous CS's.

Oh you are so nicely laidback (dare I say "reasonable"?) over there compared to some of our OBs here! Many folks here get Bios every other day at forty weeks and DAILY if they insist on going over forty-one -- combined with half hour non-stress EFMs..... It's a lot of worry, hassle, and stress! And in fee-for-service insurance plans it can add up fast at about $80 per session.

The evidence on biophysical profiles (BPPs) isn't terribly convincing. It is especially so that there is little ( i.e. - NO ) data on frequency of BPPs. Studies have tended to look at yes or no not how much !

Given that one needs to induce 500 women to prevent one stillbirth due to post-datism then the scale of any study to really answer the question is enormous.

I rarely - i.e. once a year ( that's one in ~800 cases ) request even liquor volume assessment. Full BPP is just not available. A full BPP is only ever done in UK in "ivory towers". We don't have $80 per day to spend on these cases.

Auscultated Acceleration Test (AAT)

The presence of fetal heart rate (FHR) accelerations is a well-known indicator of fetal well being, and the electronic non-stress test (NST) remains the most widely used method for detecting FHR accelerations prior to birth.  For well over a decade time-saving and economical alternatives to the NST have been studied by midwives and their colleagues as advantageous methods for the screening of low-risk women and for use in settings where technology and resources are limited (Gegor et al., 1991).  One such method, the auscultated acceleration test (AAT), is performed using a basic method of FHR auscultation via a simple, inexpensive fetoscope that costs $25-60, whereas the NST is performed via an electronic fetal monitor that costs several thousand dollars.

Paine and her multidisciplinary research team have described the development of the AAT and compared its validity to the NST in several reports since 1986 (Paine et al., 1986; Paine et al., 1986, Paine et al., 1988)./  In their most notable study, the team compared the 6-minute AAT and the NST in prediction of perinatal outcomes and found that the AAT predicted poor perinatal outcomes more accurately than the NST (Paine et al., 1992).  These studies, designed and conducted by midwives, used a wide range of providers as data collectors, including midwives, nurses, students, community health workers, and physicians.
The AAT studies conducted in the U.S. by Paine and colleagues have been replicated nationally (Daniels and Boehm, 1991) and internationally (Mahomed et al., 1992; Wu, 1991) demonstrating that the AAT is a promising low-tech, low-cost midwifery method that has distinct potential for world-wide application.

AFI - Amniotic Fluid Index

Actually, it's not placental grading that bugs me, but amniotic fluid volume estimates. One of my family doc friends once commented to me that he sees an awful lot of AF splashing around with these births in which there's supposed to be oligohydramnios.

I AGREE!!! It's happened enough that it makes me suspicious of every time I see "diminished amniotic fluid". Those numbers on the AFL are supposed to be important! But When we see a level of 8 on the u/s form and then find a POOOOL of AF at birth, how can we trust the numbers? Is it really that difficult of an estimate to make that there should be so much room for error?

I'm sure you're right. If AF is to be assessed it needs to be done by a standardised method and measure either depth of single deepest pool or AFI done in four quadrants.

The only thing I have to say about low fluid volumes is that if the docs are so worried about that with a normal, vigorous fetus, they should STOP rupturing membranes in labor and creating oligohydramnios; the very situation they induce for.

But the concern I have is the underlying cause of the oligohydramnios -- if it is due to postmaturity, and placental insufficiency, then I have observed that those are the babies with meconium and fetal distress. Those are the babies that have to be watched like a hawk in labor, and who do not withstand complicated deliveries. There certainly can be physiological problems associated with little or no water, but that, in and of itself is not usually the problem, in my opinion.

The concern with oligo is due to it's cause...placental insufficiency and the effects of this on the unborn fetus. Oligo is not caused by AROM. (BTW I am not a proponent of early inductions)

Another concern of oligo besides placental insufficiency is a cord accident. I just want to add that when you AROM you now lose the cushion around the baby and in particular the cord. How many times have you seen variables after AROM. I try to make it a practice not to AROM unless absolutely necessary.

[from ob-gyn-l]

Interested in others reliability on AFI. With the guys I take call with an AFI of 5 means certain induction, inducible cervix or not. I personally don't think AFI is that reliable and that a prolonged NST can tell you much more. I don't know what the incidence of oligo is but our radiology dept. seems to find an inordinate number of decreased AFI. What are others experience?

AFI of less than 5 is associated with a high incidence of variable decels during labor. For this reason, many feel that it is an indication for amnioinfusion. If the oligo is associated with IUGR, it is a sign of decreased renal function and hence may well be a sign of developing fetal distress.

A low AFI by itself (especially if it is 4.5) is not necessarily an indication for an induction. As with all the rest of medicine, the entire patient must be evaluated and then decide on whether or not to induce. I would never react to an AFI done by someone else. I always do my own and at the same time evaluate the rest of the feto-placental unit.(motion, breathing motion, tone, NST, & placenta)

I must agree. It seems somewhat subjective also. If the strip is reactive and cst is negative I would leave them alone if the cervix is unripe.

Personally, I place a lot of confidence in the AFI. This is from a Sonographer's perspective who has spent a lot of time studying maternal/fetal sonography... not a physician. The problem with using the 5 cm cut off is, the AFI will vary throughout pregnancy. Phelan, Ahn, Smith, et al. published a table in the J Reproduct Med. 1987, 23:610-604 that is good. I have a graph adapted from that table in FETAL SONOGRAPHY, W. B. Saunders Co. 1996. If there has been no PROM or fluid loss, then low AFI needs to be explained. Most likely it is low urine output. Either UT anomalies, which should be detectable by sonography (agenesis, hydronephrosis, large bladder, etc.). The other is some perfusion problem to the kidneys which lowers urine output. This can be far removed from the urinary tract. One of the most common is IUGR due to placental insufficiency. If there is resistance to flow through the placenta, resulting in elevated Doppler resistive indexes in the Umb. arteries, then the sphincter in the ductus venosus can redistribute the blood to the head and heart and to the disadvantage of the trunk (head sparing IUGR). At least this is the current theory. Hopefully, if you have an earlier dating sonogram, then you can compare growth intervals, if there is reduced growth, and low AFI, then I would suggest you follow *the guys [you] take call with* advice.

Increasing Amniotic Fluid Levels

Obstetrics and Gynecology 0029-7844/91/p. 1098
"Maternal Hydration Increases Amniotic Fluid Index"

"Maternal oral hydration increases amniotic fluid volume in women with decreased fluid levels."

Ob.Gyn. News Vol. 26 No. 7

"Amniotic Fluid Level Can Be Influenced by Intake of Water"

"Women with low levels of amniotic fluid can increase their amniotic fluid index for a short time by drinking more water."

Philosophy of Avoiding Induction unless Indicated

With all this talk about postdate pregnancies I thought I'd write and say just how silly I think it is to pressure a mom to go into labor by a set date when she's obviously not ready physically. By that I mean no signs of impending labor or cervical changes and a history of significantly going past her due dates. I have been in the past so pressured to have a baby by a certain time limit that I have been in tears from the threats of mandatory hospitalization, induction, and possible c/sections. Regulations saying all babies must be born by a certain date can sometimes be used to the client's detriment.

I'm due myself in about 4 days and I won't be a bit surprised if I go past my EDD. I have babies an average of 3 weeks late. No signs of postmaturity. No really long menstrual cycles (unless 28 days is long). But my mother and grandmother had healthy good-sized babies 2-4 weeks late in the days when inductions weren't common for post dates. My basal body temperature is often about 97.2-97.4, which is considered low, does this have anything to do with it?

Incidentally, I've seen 38-39 week babies with cruddy placentas that looked borderline, and 42 weekers with big juicy nice-looking placentas and no signs of being postmature, even though the due date was determined early on with U/S.

I hate to always be the voice of doom, when the subject of postmaturity comes up. However.....in my family, the story was that everyone went a month overdue. I was due on Aug 23, and was born sept 21, same with my sister, same with my aunt, when she had my cousin. So, when I went to 44 weeks with my son, part of my heart said that it was ok, because that's what women in my family do. The other part of my heart said that something was terribly wrong. My baby was born with classic postmaturity syndrome, oligohydramnios, and MAS. He had absolutely nothing wrong with him, except that he was 4 weeks overdue. He could not withstand the rigors of the cesarean, and was stillborn, 10 minutes after the surgery started.

I realize that this is anecdotal, and I realize that most post dates babies are fine. (all but one of my postdates clients has been fine -- but I have not "let" anyone get much over 42 weeks.) As a midwife, i have had to come to terms with my fears about postmaturity. However, i have learned that not every healthy, normal, well motivated, well nourished mom will have a healthy pregnancy -- once the pregnancy passes the 42 week mark. And I have learned that nature doesn't always kick in and do the "right" thing. What my own situation taught me is NOT to fear every post dates pregnancy, and NOT to induce everyone at 40 weeks, but it also taught me that sometimes testing is appropriate, and sometimes that apple does not fall, no matter how ripe. We, as careful caregivers, have to be ever watchful for the occasional at-risk baby. My first baby went 10 days over, and was fine. It was the second where my body refused to ripen. Nothing was done by the doctor to encourage labor. I would have an 18 year old son, if I had been induced at 42 weeks.

Induction is not the worst thing that can happen. My third was a section on my due date, but with my 4th I had PROM on my due date. Hard, high unripe cervix, with a -5 baby. No contractions AT ALL in the 3 days I waited. I did have a pit induction, because I didn't know about natural measures. Was not fun. For some reason, my body does not "ripen." I have quick, effective labors, once it starts, so the hormones are there, someplace. It is a mystery that I will never understand, but it has taught me the valuable lesson that nature, left alone, does not always produce a live baby. Baby squirrels sometimes fall out of the tree -- they shouldn't -- it's against their nature--but they do.

I believe that birth is safe, or I would not be a midwife. I also believe that sometimes nature needs a boost.

On the other hand, I am not defending caregivers who induce everyone by a certain date. I don't practice that way, and don't condone it.

I hardly ever encourage any kind of natural induction, can't remember when I last transported for a medical induction, and routinely let women go 42-45 wks w/ informed decision-making, home monitoring of mom and baby (BPP not easily available w/o changing all care to doc). I hardly ever see a true postmature baby, and when I have, they are usually 9/9 babies, w/ the parents wondering why we were so concerned.

Have had 2 MAS babies in 19 years of attending births (740+ births). 1 was 42 wks, looked very postmature (a healthy little 9 yr old girl now). The other was a week ago, 40 1/2 wks by US and dates, doesn't look postmature at all, still in NICU, but off the respirator as of yesterday!

I think no matter what we screen for, some babies will have problems and most all will be ok, but we'll screen and intervene trying to prevent the problems we probably can't do anything about!

I don't think this MAS baby would have made it if I hadn't had an ambubag and Neonatal resus training. First one I've not been able to get spont. respirations with at home. Great CR, but I bagged him for about the first 40 minutes till the ER crew took over. I used to be a hard-core mouth-to-mouth supporter, always carried O2, but didn't carry an ambubag till about 2 years ago. Let me tell you all I am such a believer in ambubags now. I've seen them work sooo much better than m-t-m. If you don't have one, and haven't done a Neonatal Resuscitation course, please consider doing both.

My MAS baby was only a couple of days past her due date, also. Absolutely did not have any signs of post maturity, and the amniotic water was copious and only slightly tinged yellow/green.

Our EMT response time is fast, they arrived within 5 minutes of being called, about 7 minutes after birth. I was giving baby O2 and trying to get those lungs cleaned out. She was making respiratory attempts about 4-6 times a minute on her own. Her coloring was perfect the whole time, one of the paramedics even asked me what Apgar score would I give her "A 9?", of course I was thinking a 4 (2 for color, 2 for heart rate, 0 for everything else.) In the hospital she was screaming when they poked her and the parents were told that the majority of these babies do great. The next day she took a turn for the worst, and went downhill steadily. She is severely brain damaged. And I am being sued (nothing happening currently, but there's no time limit to activate it again.)

This was a woman with NO red flags. Good attitude, good health, good nutrition, only a couple of days past due (the length of gestation was not even mentioned in the law suit). Not a hint of a problem during the pregnancy. Labor was normal, it was her first baby and she had about 24 hours of prodromal labor (<3 cm dilated) and dilated at a normal pace once active labor set in. 2nd stage was < 1 hour, I don't have her chart in front of me, but it seems like it was only 30 minutes. 9 lb. baby with no hint of shoulder dystocia.

You never know when the severely depressed/sick baby is going to show up....most likely when you least expect it!

Placental Grading

Aging of the placenta from BMJ

Fox H
Aging of the placenta
Archives of Disease in Childhood - Fetal and Neonatal Edition 1997;77:F171-F175.

Ultrasound placental grading and amniotic fluid quantitation in prolonged pregnancy.

Monaghan J, O'Herlihy C, Boylan P
Obstet Gynecol 1987 Sep;70(3 Pt 1):349-52

Ultrasound placental grading appears to offer little useful additional information to amniotic fluid quantitation in satisfactory monitoring of prolonged pregnancies.

A contemporary view of the human placenta.
Fox H
Midwifery 1991 Mar;7(1):31-9

Our current knowledge of the human placenta is briefly reviewed. Particular stress is placed upon the considerable functional reserve capacity of the placenta, the unimportance of most visible abnormalities of the placenta, the lack of any evidence that the placenta ages during gestation and the lack of significance of placental weight. The effects on the placenta of infection and of maternal cigarette smoking are considered and the concept of placental insufficiency critically discussed. It is concluded that most cases of 'placental insufficiency' are, in reality, examples of maternal vascular insufficiency resulting from inadequate placentation during the early stages of pregnancy.

[from ob-gyn-l]

Our experience suggests that the two most common associations with grade 3 placentas have been tobacco and hypertension, often undiagnosed. additionally, Vintzileos et al. suggested an increased risk of abruptio placenta with grade 3. just another $0.02. i second Mark in that pathologic correlation has been sadly lacking in the literature.

As far as placental grading is concerned the meta-analyses show it to be extremely valuable. However, no-one seems to use it. Recently on ob-gyn-l it was said that the guy who published most work on it - which had provided the material for the meta-analyses had subsequently found it not to be useful and to have abandoned it ( can't remember his name ).

Peter Grannim did the original work on placental grading while here at Yale. It was never widely used here.

Ultrasound Unreliable for Late Dating

May I suggest that you not use sonographic exams done after about mid pregnancy (or 30 weeks at the latest) to carry a fetus past term? Unless you have good dates from either an earlier sonogram (1st trimester is best) or the mother kept a very good, reliable LMP calendar, and all dates agree. If the LMP points to 42 weeks, and a 38 week sonogram points to 39 or so weeks, be very careful. It could be IUGR which a SINGLE LATE sonogram can not diagnosis. Often IUGR fetuses are stressed and can't take labor.

Obstetrician's Postdates Protocols

[from ob-gyn-l]

When are you inducing for post dates 41 or 42 weeks??

Surveillance every 48 hours if everything's OK between 41 & 42. Induction ASAP and anyway at 42. But a lot of post dates are quite in time.

My partners and I do a cervical exam and offer induction (after discussing risks:benefits) at 41 weeks if the cervix is favorable. If unfavorable, we begin twice weekly NSTs and once weekly ultrasound for amniotic fluid index and fetal weight. (If the amniotic fluid index is low-normal we may perform an ultrasound more often). At 42 weeks we encourage induction whether or not the cervix is favorable, and most patients agree to this. If not, then we continue fetal surveillance as discussed above until labor, or until low amniotic fluid or a non-reassuring NST, etc. Again, however, about 99.9% of patients want an induction by 42 weeks in our practice!

I know I've told this to you all before but all my babies go overdue by 2-3 weeks. My grandmother and mother did the same thing. My grandmother had a 10 pound baby born 1 month past her due dates. I get so sick of my caregivers getting all worked up over this. Everything else is always normal. Placentas have always been perfect. I just think some of us take longer to cook our babies. Why else would this be so common? The docs in my area set the due date as the date for induction now. No one is allowed to get to 42 weeks. I still think mine take so long because the food was good and the rent was free so they decided not to leave. Nothing else makes any more sense than that reason, so who knows?

I was a "10 MONTH" baby, as was my sister. My aunt carried her daughter "ten months."

When i got pregnant with my first, she went over 10 days. when i got pregnant with my 2nd, he was a "10 month" baby, 44 weeks. He was stillborn -- meconium, oligohydramnios, ruptured adrenal glands. He died in the 10 minutes it took to get him out by cesarean section. His heart rate had been 144. He would be 18 on the 29th of this month. As a midwife, I am cautious about inductions, and calendar watching, but postdates babies often have meconium, and sometimes don't do well in long labors. I think it is bad news for VBACs, because it gives them much less chance of delivering vaginally, if they have long labors. We just had a very postdates attempted VBAC here this week. Long labor, meconium, bad variable dips. She was transported to a doc who doesn't believe in pit for VBACs, so she had another section. I think this is a really common phenomenon. Have seen it in primips also. I assume a VERY cautious attitude with postdates moms. I also have a hard time understanding why women often sacrifice their chance for a vaginal birth, with their desired for everything to be completely natural. We have excellent tools for getting moms into labor, without pit and without AROM. Natural inductions rarely cause the same kinds of problems that medical inductions cause.

As far as post dates are concerned I let a woman go 42 weeks if primip and 43 if multip. I do not usually do anything technical to determine the welfare of the baby unless the Mom gets concerned. I firmly believe in Mom intuition. I stick to these dates because of standard of care in this community and let my Mom's know these are not engraved in stone. EVERY situation is different as is every Mom and every baby.

Our md/cnm practice does not routinely induce at any gestational age, regardless of parity. Some of the docs get nervous, and there is a pressure to induce after 42 weeks, but we try to rely on the results of testing, and not just do a knee-jerk induction.

I do, however, feel that fetal surveillance is an important component of waiting beyond 42 weeks. We do biophysical profiles to check amniotic fluid and fetal heart reactivity. Oligohydramnios is often a sign that placental function has started to decline. In my community, fetal testing is standard of care, and oftentimes results in postdates inductions. The unfortunate happening is that postdates babies may die if not followed carefully. We are happy to wait, but only with assurance that the fetus is fine!

Postdates and Thyroid

I am formulating a theory and would be interested in seeing if a study could be done re: a possible link between postdatism and low thyroid function.

I have suspected a link.

Due to the stringent laws re postdates here in AZ, I rarely have anyone go >42 weeks.( Thanks to the castor oil and B &B routine) In my 20 years of practice, I've had 3 that have had to be "terminated" for hospital delivery. One of the moms was soon after diagnosed with hypothyroid, and both other babies were initially low on the TSH on the metabolic screen.

I've also had several other low TSH with home borns at 41.6 weeks. But all were normal by the second screen.

I attended a conference sponsored by the Phoenix perinatologists in which one of the presentations on postdates included a correlation between postdates and babies with low thyroid function. Also said that postdates babies are twice as likely to be boys. Have any of you noticed that?

I would like to thank you for studying this subject because I agree with your theory from my own experience and am finally glad that someone is taking a look at this problem.

I delivered four children from 1972 until 1981 and all were considered "past due" - between 2 and four weeks after due date.  At the time I was not yet diagnosed with hypothyroid and my obstetrician never even considered the possibility.  My first baby was 8 lbs. 5 oz. and the others that followed were increasingly larger.  My last baby weighed in at 10 lbs. 5 oz.

I have always believed that my low thyroid was the reason for my post date deliveries and larger than average babies.


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