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Obesity Increases Miscarriage Risk

This case-control study showed increased risk for early and recurrent early losses in women with BMIs over 30.

Obesity is a major health problem. In the U.K., for example, 20% to 25% of women are considered obese (BMI, >30 kg/m²), and obese women are at increased risk for infertility and poor pregnancy outcomes. To determine the impact of obesity on risk for spontaneous abortion, researchers reviewed data on women giving birth at one U.K. hospital from 1985 to 1999. BMI at 10 to 14 weeks' gestation was determined, and 1644 obese women were matched by age to 3288 normal-weight controls (BMI, 19-24.9 kg/m²).

Early miscarriage (6-12 weeks' gestation), late miscarriage (12-14 weeks' gestation), and recurrent early miscarriage (>3) occurred in 12.5%, 2%, and 0.4% of obese women, respectively. In the control group, the respective percentages were 10.5%, 2%, and 0.1% (relative risks, 1.25, 1, and 4). Thus, obese women were significantly more likely than controls to have early losses (odds ratio, 1.2) and recurrent early losses (OR, 3.51). The prevalence of diabetes in the two groups was low and did not explain the results.

Comment: Although it is not necessarily fashionable to implicate obesity in increased fetal and embryonic risk, accumulating evidence supports a causal relation between obesity and adverse pregnancy outcomes. Findings from this well-done study show that obese women are at increased risk for miscarriage, sporadic as well as recurrent. This report need not unduly alarm our patients, but it does provide another reason for them to drop their weight to standard recommended levels.

— Sandra Ann Carson, MD

Published in Journal Watch Women's Health October 6, 2004

Citation(s):

Lashen H et al. Obesity is associated with increased risk of first trimester and recurrent miscarriage: Matched case-control study. Hum Reprod 2004 Jul; 19:1644-6.

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