Post-Term Delivery Predicts Subsequent Late Birth

Study finds that women with one post-term birth have an almost twofold risk of another such birth

WEDNESDAY, March 7 (HealthDay News) -- Women with a history of post-term birth have a nearly twofold risk of a subsequent post-term birth, suggesting that genetic or other common factors may influence the likelihood of abnormal parturition timing, according to a report published in the March issue of the American Journal of Obstetrics & Gynecology.

Louis J. Muglia, M.D., Ph.D., of the Washington University School of Medicine in St. Louis, and colleagues evaluated data from the Missouri Department of Health on 368,633 births, 7.6 percent of which occurred after 42 weeks' gestation.

Independent of race, the researchers found that mothers with an initial post-term birth had a higher risk for a subsequent post-term birth than those who did not (odds ratio, 1.88). The investigators also found that the risk of post-term birth was positively associated with maternal education of less than 12 years (adjusted OR, 1.51) and a maternal body mass index higher than 35 kg/m2 (adjusted OR, 1.23). Black women had a lower risk for all or recurrent post-term births, the report indicates.

"In contrast to preterm birth, in which a variety of contributors such as drug use, infection, and placental abruption could precipitate labor, the failure to enter labor may define a more homogenous physiologic condition regarding the clock mechanism that times the duration of gestation," the authors conclude.

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