The relationship between body mass index and unintended pregnancy: results from the 2002 National Survey of Family Growth

Background: The study was conducted to characterize the relationship between body mass index (BMI) and unintended pregnancy, contraceptive use patterns, and perceived fertility. Methods: This study employed a cross-sectional, nationally representative database (2002 National Survey of Family Growth). Unintended pregnancy was compared among BMI groups [normal (<25 m/kg²), overweight (25-30 m/kg²) and obese (>30 m/kg²)]. Analyses also evaluated the association between demographic, socioeconomic, behavioral and health-related variables and BMI. Multiple logistic regression with adjustment for sampling design was used to measure associations of interest. Results: BMI data were available from 6690 nonpregnant women. Of these, 3600 (53.6%) were normal weight, 1643 (25%) were overweight and 1447 (21.4%) were obese. Compared to women with normal BMIs, the risk of unintended pregnancy in the last 5 years did not differ among overweight [adjusted OR 0.95 (95% CI 0.77-1.17)] or obese [adjusted OR 0.87 (95% CI 0.70-1.09)] women. There were no differences in contraceptive use patterns or perceived fertility among BMI groups. Conclusion: Data from the 2002 NSFG do not support an association between obesity and unintended pregnancy.