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Chromosomal Abnormalities, Miscarriage More Likely After 40

TUESDAY, Feb. 27, 2018 -- Pregnant women older than 40 years have a higher risk of chromosomal abnormalities, miscarriage, and preterm birth compared to younger women but not congenital malformations or stillbirth, according to a study published online Feb. 5 in Obstetrics & Gynecology.

Line Elmerdahl Frederiksen, from Aarhus University in Denmark, and colleagues used a nationwide cohort of 369,516 singleton pregnancies in Denmark. Pregnant women aged 35 and older were categorized into two advanced maternal age groups -- 35 to 39 years and ≥40 years -- and their pregnancy outcomes were compared with those of pregnant women aged 20 to 34 years.

The researchers found that of the women ≥40 years, 10.82 percent experienced one or more of the selected adverse pregnancy outcomes versus 5.46 percent of pregnant women aged 20 to 34 years (odds ratio [OR], 2.02). Specifically, pregnant women ≥40 years had a higher risk of chromosomal abnormalities (3.83 versus 0.56 percent; OR, 7.44), miscarriage (1.68 versus 0.42 percent; OR, 3.1), and birth before 34 weeks of gestation (2.01 versus 1.21 percent; OR, 1.66) compared with women aged 20 to 34 years. However, women ≥40 years did not have an increased risk of congenital malformations or stillbirth.

"Several factors increase the risk of adverse pregnancy outcomes, but advanced maternal age drives a high proportion of the total risk score," the authors write.

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Posted: February 2018

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