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Fewer infant deaths during ‘39-week rule’ era



– Closer adherence by U.S. physicians to the “39-week rule” for elective deliveries appears to have cut net neonatal mortality in an analysis of more than 14 million deliveries during 2008-2012.

This net drop in mortality occurred despite a concurrent rise in stillbirths, Rachel A. Pilliod, MD, said at the annual Pregnancy Meeting sponsored by the Society for Maternal-Fetal Medicine. The increase in stillbirths was more than counterbalanced by a larger drop in infant deaths during the same period.

Dr. Rachel A. Pilliod Mitchel L. Zoler/Frontline Medical News

Dr. Rachel A. Pilliod

Despite the overall net decline in U.S. neonatal mortality coincident with improved adherence to the rule to wait until 39 weeks gestation before proceeding with an elective delivery, the increased number of stillbirths was “unacceptable,” said Dr. Pilliod of Oregon Health and Science University, Portland.

“It’s not a one-to-one trade, where each stillbirth corresponds to an infant death that is subsequently avoided. It’s hard to make this trade-off when counseling parents,” she said. “We think that there has been some effect from increasing gestational age on reducing overall mortality, but we need to do even better on identifying high risk [deliveries].”

What is “unacceptable,” Dr. Pilliod said, is if a woman needs an earlier delivery but it gets pushed back because of a poorly informed application of the 39-week rule.

Her study used data collected by the National Center for Health Statistics on U.S. deliveries each year, focusing on pregnancies that were singletons and nonanomalous.

She compared the 7,388,782 deliveries during 2008 and 2009 and 6,980,962 births during 2011 and 2012, selecting the 2-year time periods on either side of the Joint Commission’s 2010 adoption of a quality measure aimed at decreasing elective deliveries prior to 39 weeks gestation.

The Joint Commission’s action had its desired effect. Deliveries at 39 weeks jumped from 36% of all elective births in 2008 and 2009 to 43% in 2011 and 2012, while deliveries at 38 weeks show the biggest drop, from 22% to 20%, Dr. Pilliod reported (Am J Obstet Gynecol. 2017 Jan. doi: 10.1016/j.ajog.2016.11.959).

Concurrent with the rise in 39-week births and a drop in neonates with shorter gestation times, the incidence of stillbirths rose from 9.32 per 10,000 births in 2008 and 2009 to 10.15, an increase of 0.83 per 10,000 births.

But during the same periods the incidence of infant deaths fell, from 20.63 per 10,000 births in 2008 and 2009 to 19.0 in 2011 and 2012, a reduction of 1.63 per 10,000. Overall the stillbirth and infant death data combined for a net mortality reduction of 0.8 per 10,000 births.

On Twitter @mitchelzoler

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