Home Family Practice Chromosomal Abnormalities, Miscarriage More Likely After 40

Chromosomal Abnormalities, Miscarriage More Likely After 40

But older women have no increased risk of congenital malformations, stillbirth versus those aged 20-34

TUESDAY, Feb. 27, 2018 (HealthDay News) — 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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