In the News
In 2011 the National Institute of Child Health and Human Development recommended that nonmedical deliveries before 39 weeks’ gestation be avoided. This became known as the “39-week rule.” But some practitioners have expressed concern that waiting until then could increase the risk of stillbirth. In two new studies, researchers compared U.S. stillbirths in relation to gestational age to determine rates of stillbirth.
MacDorman and colleagues used data on 50,045 stillbirths and 8,268,441 live births that occurred in 2006 and 2012. Stillbirth rates had increased at 34 to 36, 37, and 38 weeks of gestation in 2012 and were slightly, though not significantly, lower at 39 weeks. Marian MacDorman, lead author of the study, cautions, “We're not making recommendations on the timing of delivery for all pregnancies. Preterm birth is often medically indicated to save babies’ lives and [reduce] morbidity.” The findings “don't mean to never deliver before 39 weeks,” MacDorman says, “but rather, don't do elective deliveries before 39 weeks.”
Little and colleagues looked at stillbirths in all 50 states and the District of Columbia from 2005 to 2011, using information from birth and death certificates. The stillbirth rate didn't change, even in states with programs to reduce early-term deliveries. In women with diabetes, however, stillbirths did increase 25%. The growing severity of diabetes-related morbidity is likely connected to the nation's epidemic of obesity, and the possibility of a connection to stillbirths warrants more study.
Although neither study found an increase in the risk of stillbirths after 39 weeks, “pregnancies with fetal or maternal medical complications should be managed by condition-specific guidelines” and not governed by the 39-week rule, says Jennifer Bailit of Case Western Reserve University School of Medicine, who cowrote an accompanying editorial. Guidelines on complications of pregnancy, such as preeclampsia and hypertension, are available from the American College of Obstetricians and Gynecologists (see www.acog.org).—Carol Potera
MacDorman MF, et al. Obstet Gynecol
2015;126(6):1146-50; Little SE, et al. Obstet Gynecol
2015;126(6):1138-45; Bailit JL, Lappen JR Obstet Gynecol. 2015;126(6):1131–2