(HealthDay)—From 2007 to 2015 there was an increase in the proportion of births at gestational age 39 to 40 weeks, and perinatal mortality at this gestational age decreased, according to a study published online May 14 in JAMA Pediatrics.
Cande V. Ananth, Ph.D., M.P.H., from Columbia University in New York City, and colleagues conducted a retrospective cohort study to examine trends in U.S. perinatal mortality by linking live birth and infant death data from Jan. 1, 2007, through Dec. 31, 2015.
The researchers observed a decrease in the proportion of births at all gestational ages among the 34,236,577 singleton live births during the study period, except for at 39 to 40 weeks, which increased from 54.5 to 60.2 percent. There was a decrease in perinatal mortality from 9.0 to 8.6 per 1,000 births. There were decreases in stillbirths, from 5.7 to 5.6 per 1,000 births, and in neonatal mortality, from 3.3 to 3.0 per 1,000 births. The proportion of births at gestational ages 39 to 40 weeks increased, but there was an annual relative adjusted decline of −1.3 percent in perinatal mortality. The decrease in neonatal mortality was mainly due to alterations in the gestational age distribution.
"Although the proportion of births at gestational age 39 to 40 weeks increased, perinatal mortality at this gestational age declined," the authors write.
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