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More Discussion Regarding Link Between Ultrasound and IUGR

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An interactive resource for moms on easy steps they can take to reduce exposure to chemical toxins during pregnancy.

Other excellent resources about avoiding toxins during pregnancy

These are easy to read and understand and are beautifully presented.

Also, I found that article about the danger of frequent ultrasounds. It says the FDA has recommended not using routine ultrasound unless there is bleeding, history of birth defects, or "other possible dangers". This is supposedly "due to the fact that ultrasound waves are known to generate heat. The heat may cause microscopic bubbles in body fluids of the fetus to oscillate and collapse. Further research is being conducted on whether this condition could harm the baby. Additional concerns arose when studies showed a possible link between ultrasound and growth retardation in the fetus. This factor was noticed in animals which had been exposed to frequent ultrasound imaging similar to that which is performed on humans.

The same condition was observed in the development of unborn babies in a group which underwent five or more ultrasound imaging and Doppler studies between 18 and 38 weeks. In this group, the proportion of growth-restricted fetuses was increased by one third, as opposed to a second group which received either no imaging study or a single one at 18 weeks gestation, in which no significant changes were noted."

References: "Routine Ultrasound in Pregnancy" HealthFacts, Sept. 1993, p. 2

Science News, April 4, 1992, p. 218-219

British Medical Journal, July 3, 1993, p. 13

"Effects of Frequent Ultrasound During Pregnancy:  A Randomized

Controlled Trial," Lancet Medical Journal, Vol. 342, Oct. 9, 1993, p.



The message started by asking "Remember that ultrasound discussion?" and then quoted someone else's message. This message referred to four references. It stated in part that the research showed a link between sonography and IUGR. However, on close reading I do not believe that is what the article states. The main article is from Newnham, Evans, Michael, et al.; "Effects of frequent ultrasound during pregnancy: a randomised controlled trial"; Lancet 342:887-891, Oct. 9, 1993. The research was from Australia, that and the fact it was in Lancet speaks well of the results. Australia has always been a leader in Diagnostic Medical Sonography. The research compared an "intensive" group (1415) who received 5 or more sonographic examinations during a pregnancy to a "regular" group (1419) who received only one routine exam. The comparison was to determine if intensive sonographic observation "...would improve pregnancy outcome expressed as days of neonatal stay and the rate of pre-term birth."

However, the message's knee-jerk conclusion of the out of context quotations were off base. The real results were:

  1. "The duration of neonatal stay and rate of pre-term birth, which were the principal end points of this trial, were similar in the two groups."
  2. In addition they found "There were also no differences in Apgar scores, cord arterial blood-gas values, frequency and type of neonatal resuscitation, proportion and duration of admissions to the neonatal intensive care unit, requirements for ventilation and oxygen, and the proportions with hyaline membrane disease, intraventricular hemorrhage, seizures and bronchio-pulmonary dysplasia."
  3. "Gestational age at birth and the proportions and types of congenital abnormalities were similar in the two groups."
  4. "There were ten neonatal deaths in the regular group and three in the intensive." (The message referenced above did not point out that those who received more ultrasound had less than a 1/3 the number of deaths. This was a random event of congenital abnormalities and pre-term birth, and had nothing to do with the number of sonograms.)
  5. "The mean birthweight in the intensive group was 25 g less than the regular group, although this difference was not statistically significant." This is the ONLY part of the report that the messenger locked onto. Later in the Discussion the authors stated, "Examination of percentile shifts indicates the effect was not a general decrease in growth of all fetuses, but rather a displacement of some babies into lower centile groups."
It appears that the fetuses in the "regular" group who had problems died while those with problems in the "intensive" group did not. They go on to state that "Those pregnancies in which the fetus was believed to be growth restricted were often the referred for extra examinations. Thus, any attempt to show a dose response would be biased." In other words sonography found the fetuses with problems and they got better prenatal care as a result.

I do not believe this study shows any detrimental results from the use of sonography. Any conclusion to the contrary must take parts of the study out of context, is misleading, and unnecessarily anxiety producing. The research was good, the interpretation given in the message was not.

This Web page is referenced from another page containing related information about Prenatal Screening for Birth Defects/Ultrasound


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