Body mass index and risk of miscarriage in women with recurrent miscarriage

Objective To investigate the effect of underweight, overweight, and obesity on the risk of miscarriage in the subsequent pregnancy in women with recurrent miscarriage. Design Retrospective analysis of prospectively collected data from the database of a tertiary recurrent miscarriage center. Setting The recurrent miscarriage clinic at Sheffield Teaching Hospitals. Patient(s) A total of 844 pregnancies from 491 patients with recurrent miscarriage were included in the analysis. Main Outcome Measure(s) The odds of miscarriage in the subsequent pregnancy for all pregnancies after referral to the recurrent miscarriage clinic as well as the first pregnancy post referral. Result(s) When analyzing all pregnancies, and compared to women with a normal body mass index, obese and underweight patients had a significantly higher odds of miscarriage in the subsequent pregnancy (OR, 1.71; 95% CI, 1.05–2.8; and OR, 3.98; 95% CI, 1.06–14.92; respectively), whereas there was no significantly increased odds of miscarriage in overweight women (OR, 1.02; 95% CI, 0.72–1.45). Logistic regression analysis showed that the most important factor predicting the occurrence of miscarriage was advanced maternal age ( P =0.01) followed by an increased body mass index ( P =0.04). Conclusion(s) In women with recurrent miscarriage, a mild increase in the body mass index does not increase the risk of miscarriage, whereas obese and underweight patients have a small but significant increased risk of miscarriage in the subsequent pregnancy.