WEDNESDAY, Aug. 8 (HealthDay News) -- For babies who are born very prematurely, vaginal deliveries are as safe as C-sections as long as the infants are in the head-first position in the womb, a new study indicates.
The same does not hold true for babies in the breech position who are delivered at less than 32 weeks gestation. Researchers found these infants had a significantly lower risk of death when they were delivered during a planned C-section.
The study was published in the current issue of the American Journal of Obstetrics & Gynecology.
"Selecting a route of delivery at less than 32 weeks' gestation is a difficult clinical decision, given the high rate of infant mortality and morbidity, as well as the maternal risks associated with Cesarean delivery," lead investigator Dr. Uma Reddy, of the Eunice Kennedy Shriver National Institute of Child Health and Human Development at the National Institutes of Health, said in a journal news release.
Researchers examined data from an existing study that compiled information on more than 200,000 deliveries that occurred between 2002 and 2008 from 12 clinics and 19 hospitals in the United States.
They took into account the reason for premature delivery, including early labor, women's water breaking early or other health issues of the women or their babies, such as preeclampsia, placental abruption or severe maternal medical disease.
The researchers found that issues with the mothers or their babies were responsible for 45.7 percent of the premature deliveries. Women's water broke early in 37.7 percent of the deliveries, and women went into preterm labor in 16.6 percent of cases. The study noted that preeclampsia and major birth defects were the leading contributors to early preterm births due to problems that put a woman or her baby at risk.
The researchers then analyzed nearly 3,000 pregnancies involving one baby that was anywhere from 24 weeks to one day shy of 32 weeks gestation. All of the babies were eligible for a vaginal birth or C-section.
After comparing the outcomes of the vaginal births with planned C-sections, the researchers divided the deliveries into two groups based on how premature the babies were: 24 to almost 28 weeks and 28 weeks to almost 32 weeks.
The study found that vaginal deliveries for babies in the earlier preterm group who were in the head-first position did not affect death rates for the infants. The researchers noted more than 80 percent of the vaginal births were successful.
If the babies were in breech, however, most deliveries were by planned C-section. The researchers pointed out that only 27.6 percent of vaginal births attempted in these cases were successful.
For babies born at a gestation of 28 to almost 32 weeks, vaginal births and C-sections had the same neonatal death rate as long as the baby was head first. For breech babies, neonatal mortality was 6 percent for vaginal deliveries compared to 1.5 percent for C-sections.
"The detailed information in our study -- not available in birth certificate data -- enabled us to account for the effect of attempted route of delivery and indications for delivery on neonatal mortality," Reddy concluded. "This information has direct clinical applications and is crucial for counseling families about the benefits and risks of attempting vaginal delivery in this situation."
The U.S. Centers for Disease Control and Prevention has more on premature birth.
-- Mary Elizabeth Dallas
SOURCE: Elsevier, news release, Aug. 6, 2012
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