Pregnancy Intention and Contraceptive Use among Women by Class of Obesity: Results from the 2006-2010 and 2011-2013 National Survey of Family Growth.

OBJECTIVE

Conflicting research findings on the association of obesity and pregnancy intention may be due to their collective definition of obesity at a body mass index of 30 kg/m or greater. However, obese women with a BMI of 40 kg/m or greater may be both behaviorally and clinically different from obese women with a lower BMI. This study reexamines this relationship, stratifying by class of obesity; the study also explores variations in contraceptive use by class of obesity given their potential contribution to the incidence of unintended or unwanted pregnancy.

METHODS

This study combined data from the 2006 through 2010 and 2011 through 2013 US National Survey of Family Growth. Pregnancy intention (intended, mistimed, unwanted) and current contraceptive use (no method, barrier, pill/patch/ring/injection, long-acting reversible contraceptive, sterilization) were compared across body mass index categories: normal (18.5-24.9 kg/m kg/m), overweight (25.0-29.9), obese class 1 (30.0-34.9 kg/m), class 2 (35.0-39.9 kg/m), and class 3 (≥40 kg/m, severe obesity). Weighted multinomial logistic regressions were refined to determine independent associations of body mass index class and pregnancy intention, as well as contraceptive method, controlling for demographic, socioeconomic, and reproductive factors.

RESULTS

Body mass index data were available for 9,848 nonpregnant, sexually active women who reported not wanting to become pregnant. Women with class 3 obesity had significantly greater odds of mistimed (adjusted odd ratio [aOR], 1.67; 95% confidence interval [CI], 1.02-2.75) or unwanted (aOR, 1.96; 95% CI, 1.15-3.32) pregnancy compared with normal weight women. Women with class 2 or 3 obesity were more likely to not be using contraception (aOR, 1.53-1.62; 95% CI, 1.04-2.29). Although women with class 2 obesity were more likely to be using long-acting reversible contraceptive methods and sterilization over short-acting hormonal methods (aOR, 1.67; 95% CI, 1.08-2.57; aOR, 2.05; 95% CI,1.44-2.91), this association was not observed among women with class 3 obesity.

CONCLUSIONS

Women with class 3 obesity are at greater risk of unintended pregnancy and are less likely to be using contraception than normal weight women. Whether these findings are related to patient and/or provider barriers that are not as visible among women with class 1 and class 2 obesity warrants further investigation.