Obesity is associated with increased risk of first trimester and recurrent miscarriage: matched case-control study.

BACKGROUND: Obesity has become a major health problem worldwide and is also associated with adverse pregnancy outcome. The aim of this study was to assess the impact of obesity on the risk of miscarriage in the general public.

METHODS: This was a nested case-control study. The study population was identified from a maternity database. Obese [body mass index (BMI) >30 kg/m2] women were compared with an age-matched control group with normal BMI (19-24.9 kg/m2). Only primiparous women were included in the study to avoid including the subject more than once, and to be able to correctly identify recurrent miscarriages. The prevalence of a previous history of early (6-12 weeks gestation), late (12-24 weeks gestation) and recurrent early miscarriages (REM) (more than three successive miscarriages <12 weeks) was compared between the two groups.

RESULTS: A total of 1644 obese and 3288 age-matched normal weight controls with a mean age of 26.6 years [95% confidence interval (CI) 26.5-26.7] were included in the study. The risks of early miscarriage and REM were significantly higher among the obese patients (odds ratios 1.2 and 3.5, 95% CI 1.01-1.46 and 1.03-12.01, respectively; P = 0.04, for both].

CONCLUSIONS: Obesity is associated with increased risk of first trimester and recurrent miscarriage.