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Risk for stillbirth increases with length of pregnancy
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The risk for stillbirth increased as a pregnancy continued, particularly after 40 weeks gestation, increasing 64% from week 40 to week 41, according to study results published in PLOS Medicine.
The risk for neonatal mortality increased after 41 weeks gestation, according to study findings.
“Despite advances in antenatal and intrapartum care, stillbirth continues to be a major burden,” Javaid Muglu, MD, of the women’s sexual health division of University Hospital Lewisham, Lewisham and Greenwich NHS Trust, London, and colleagues wrote. “More than 3,000 babies are stillborn every year in the U.K. — with a third of them considered to be apparently healthy term infants (37 weeks gestation or beyond).”
Researchers conducted a meta-analysis of cohort studies on term pregnancies that included information on stillbirths and neonatal deaths by gestational week. Online searches were conducted on Medline, Embase, and Google Scholar to identify studies between January 1990 and October 2018.
After exclusions, 13 studies from high-income countries with data on 15,124,027 pregnancies, 17,830 stillbirths and 2,348 neonatal deaths were included in the study.
Researchers found that the risk for stillbirth increased from 0.11 per 1,000 pregnancies at 37 weeks (95% CI, 0.07-0.15) to 3.18 per 1,000 pregnancies at 42 weeks (95% CI, 1.84-4.35).
Compared with delivery at 40 weeks, the risk for stillbirth increased by 64% (RR = 1.64, 95% CI 1.51-1.77) in pregnancies that continued to 41 weeks. An additional stillbirth occurred with every 1,449 women (95% CI, 1,237-1,747) who continued pregnancy from 40 to 41 weeks.
A subgroup analysis found that black women were 1.5 to 2 times more likely to have a stillbirth at any gestational age compared with white women.
The risk for neonatal death did not change from 38 to 41 weeks of gestation, but significantly increased after 41 weeks (RR = 1.87;95% CI, 1.07-2.86).
“Any discussion with women considering prolonging their pregnancy beyond 41 weeks gestation should include information on the absolute risk increase, and the effects of induction of labor on mode of delivery and perinatal outcomes,” Muglu and colleagues wrote. “There is a need to assess the acceptability of early delivery at term to parents and healthcare providers to avoid the small risk of stillbirth.”– by Erin Michael
Disclosures: The authors report no relevant financial disclosures.