Pregnancy History as an Important Predictor of Body Mass Index (BMI) in 45–54 Year-old Women (P21-047-19)

Abstract

Abstract Objectives In mid-life, women have elevated risks of cardiovascular and metabolic diseases. Pregnancy causes substantial metabolic changes in women, but it is unclear whether these changes persist life-long. Thus, we investigated associations between pregnancy history and mid-life overweight/obesity, accounting for the menopausal transition. Methods Pre- and peri-menopausal women (ages 45–54, n = 772) in the Baltimore Mid-Life Women's Health Study reported their demographics, health habits, and pregnancy history (numbers of live births/pregnancies and age at first birth/last pregnancy) via questionnaires. Height and weight were measured to calculate BMI. Multivariable logistic regression models assessed overall and stratified (by menopausal status) associations of pregnancy history and risk of mid-life overweight/obesity (BMI ≥ 25 kg/m2), controlling for race, employment, health, alcohol intake, smoking status, physical activity, and menopausal status (unstratified models). Results Women had a median age of 48, 65% were pre- and 35% were peri-menopausal, 65% were white, 63% had graduated college, and 74% had a family income ≥$50,000. Mean (SD) BMI was 28.5 (7.4) kg/m2, and was higher in peri- vs. pre-menopausal women (29.8 vs. 27.8 kg/m2; P < 0.005). Ages at first birth or last pregnancy were not associated with mid-life BMI. Women whose pregnancies either did or did not result in a live birth had 44% (OR: 0.56; 95% CI: 0.32, 0.99; P < 0.05) and 59% (OR: 0.41; 95% CI: 0.19, 0.87; P < 0.05), respectively, lower odds of being overweight/obese at age 45–54 compared to women who had never been pregnant. However, in women who had been pregnant, the odds of being overweight/obese increased by 19% with every live birth (OR: 1.19; 95% CI: 1.02, 1.40; P < 0.05). In stratified analyses, these associations remained significant only in pre-menopausal women. Conclusions In pre-menopausal women, having a history of pregnancy appears to be protective against overweight/obesity, but the protective effects diminish with every live birth. In peri-menopausal women, pregnancy history was not related to BMI, suggesting the importance of other lifestyle or physiological factors in determining BMI during menopause. The discrete findings in pre- vs. peri-menopausal women warrant studies examining relationships of pregnancy history with BMI after menopause. Funding Sources This study was made possible by funding from NIH/NIEHS, USDA, and Michigan AgBioResearch.