The gentlebirth.org website is provided courtesy of
Ronnie Falcao, LM MS, a homebirth midwife in Mountain View, CA

Explanation of Late Decels

How serious are late decels following a contraction? Assuming that it's a natural contraction, not pit-induced, what do you think should be done about them? How many does it take to get you alarmed?

A single isolated late decel (caused by ANY type of contraction-pit or no) shouldn't ALARM you.....but rather cause you to look at the overall pattern the baby has had up to this point. If there has been GOOD variability and accelerations.....an isolated late decel is not something to worry about. However, if there hasn't been variability or minimal variability with no accels and the lates start occurring more frequently....this can be very worrisome. Part of the definition of a "late" decel is that it continues *after* a contraction. A decel that resolves by the end of the contraction is not a late deceleration. It doesn't matter if it is a pit-induced or "natural" contraction.

You also need to look at what's going on with the labor and mom if you're getting late decels. Has she been hyperventilating (or breath holding) and not perfusing her placenta? Is she dehydrated and/or febrile? What stage of labor are we at? Has some intervention/procedure just occurred- the bag of waters breaking (spontaneously counts too!), pain medication, an epidural, bladder being emptied (and mom doing it "naturally" counts too!), position changes (doesn't matter if it's supposed to be a "good" position for labor if the baby isn't going to tolerate it!) etc etc Is there anything that we can do to prevent/ resolve any further decels- position changes, hydration (oral is slow....IV much quicker), oxygen to mom (nasal cannulas don't get anywhere near enough O2 to hyperoxygenate a laboring mom, and should NEVER be used in a labor situation for fetal distress), STOPPING or decreasing the contractions for less stress on baby, fetal scalp stimulation or sampling to assess for reactivity and fetal blood gases (oxygenation, carbon dioxide=poison, bicarbonate level=fetal "waste" products, base excess= "reserve"), or anything else to "fix" the lates?

Generally speaking, repetitive late decels with minimal-to-absent variability are a BIG RED FLAG that needs to be investigated and resolved. If the baby has looked good up to this point and there are no extenuating circumstances (maternal or OB complications) then once a baby starts to look "bad" , he/she usually has about 20-30min of "reserve" left in the placenta. If the pattern resolves.....great! You can replenish that reserve over time. If the worrisome pattern continues or worsens despite all the usual intrauterine resuscitation measures ....you'd better start making sure you can get the baby OUT in that period of time. The variability is a much more sensitive reflection of fetal oxygenation than just late decels.....it's more of an overall picture and not just one item. You can have repetitive late decels with good variability and probably have a GREAT baby outcome. You could have no decels and no variability and end up with a LOUSY baby outcome. And unfortunately, variability can be very hard to assess using external, noninvasive methods (fetoscopes, Dopplers, stethoscopes) and external fetal monitors only show long-term variability and don't tell anything about short-term (beat-to-beat) variability.