Prior Miscarriages Up Risk for Down Syndrome, Aneuploidy

Women with three prior spontaneous abortions have 47 percent higher risk of fetus with Down syndrome

WEDNESDAY, May 3 (HealthDay News) -- Women with a history of miscarriage may have an increased risk for fetal aneuploidy including Down syndrome in subsequent pregnancies, according to a report in the May issue of Obstetrics & Gynecology.

Katherine Bianco, M.D., and colleagues from the University of California San Francisco, conducted a retrospective cohort study of 46,939 women who underwent fetal karyotype analysis and had a known obstetric history. The risk for aneuploidy increased with number of prior spontaneous abortions, for a risk of 1.39 percent with no prior miscarriage, 1.67 percent for one, 1.84 percent for two and 2.18 percent for three.

After controlling for age, parity and other factors, they estimated that three prior spontaneous abortions would increase the chance for Down syndrome by 47 percent and all aneuploidy by 51 percent. For women who were aged 35 years or older the risks further increased to 56 percent and 68 percent, respectively.

Although the authors believe the link between history of spontaneous abortion and risk for aneuploidy should be confirmed in low-risk populations, they suggest the information may be useful for prenatal diagnostic counseling. They estimate that a woman with a fetal Down syndrome risk of one in 300 would have a risk of one in 204 with a history of three prior spontaneous abortions.

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