Associations of Pregnancy History with BMI and Weight Gain in 45–54-Year-Old Women

Abstract

Background Midlife women have a higher risk of cardiometabolic disease than younger women, but the lifelong biological/lifestyle factors responsible for this increase are unclear. Objectives We investigated whether pregnancy history is a risk factor for midlife overweight/obesity and evaluated potential hormonal mechanisms. Methods The Baltimore Midlife Women's Health Study, a prospective cohort, recruited 772 women aged 45–54 y. Women reported pregnancy characteristics via questionnaires, trained staff measured weight/height to calculate midlife BMI, and serum hormones were assessed by ELISA. Logistic regression models assessed associations of pregnancy history with risk of midlife overweight/obesity and BMI gain since age 18. We additionally explored whether associations differed by menopausal status, and whether midlife hormones mediated relationships of pregnancy history and midlife BMI. Results These premenopausal or perimenopausal women were 66% Caucasian/White and 30% African American/Black, with a median of 2 live births (range: 0–11) and median age at first birth of 27 y (range: 12–46 y). Women with 0 and ≥2 live births had lower odds of overweight/obesity than those with 1 birth (OR = 0.47; 95% CI: 0.23, 0.96; P = 0.04, and OR = 0.58; 95% CI: 0.35, 0.95; P = 0.03, respectively). Women with ≥2 live births also had lower odds of BMI gain than those with 1 birth (OR = 0.66; 95% CI: 0.41, 1.06; P = 0.08). Furthermore, women who were older at their first birth had lower odds of overweight/obesity (OR = 0.96; 95% CI: 0.92, 1.00; P = 0.03) and BMI gain (OR = 0.97; 95% CI: 0.93, 1.00; P = 0.06). Number of pregnancies and age at last pregnancy were not associated with midlife overweight/obesity or BMI gain. Associations did not differ by menopausal status and were not explained by midlife hormones. Conclusions Earlier childbirth and having 1 child increased women's risk of midlife overweight/obesity and BMI gain since age 18. Additional studies should focus on women's childbearing years as a critical determinant of midlife metabolic health.

Duration of Lactation and Maternal Risk of Metabolic Syndrome: A Systematic Review and Meta-Analysis

“…In 2016, 40% of women globally, aged >18 years, were overweight [ 13 ], and women who enter menopause, being overweight or obese, are at great risk for cardiometabolic disruptions [ 14 ]. Metabolic syndrome (MetS) is a cluster of risk factors for CVD, consisting of metabolic abnormalities, such as abdominal obesity, dyslipidemia, hypertension, and hyperglycemia [ 15 , 16 ].…”

Adverse generational changes in obesity development converge at midlife without increased cardiometabolic risk

“…A study in middle‐aged retired US women reported that women had a 7% increase in obesity for each additional child born, even after controlling for potential confounders ( 30 ). From a biological point of view, this positive association of parity and obesity can be explained by the numerous metabolic changes that occur during the pregnancy and can persist even after, including insulin resistance and fat accumulation ( 31 , 32 ).…”

Midlife Urinary Phthalate Metabolite Concentrations and Prior Uterine Fibroid Diagnosis

“…To evaluate differences in associations between phthalate biomarker concentrations and prior fibroid diagnosis by changes in BMI from age 18 to 45–54 (second objective), we first classified both midlife BMI and BMI at age 18 using the following clinical categories [ 40 ]: under-/normal weight (<25 kg/m 2 ) and overweight/obese (≥25 kg/m 2 ). Then, we categorized changes in BMI as follows: women who remained overweight/obese through age 45–54 (overweight/obese at ages 18 and 45–54), women who became overweight/obese by age 45–54 (under-/normal weight at age 18 but overweight/obese at age 45–54), women who remained under-/normal weight through age 45–54 (under-/normal at ages 18 and 45–54), and those who became under-/normal weight by age 45–54 (overweight/obese at age 18 but under-/normal weight at age 45–54) [ 41 ]. In these models, we included a multiplicative interaction between phthalates and change in BMI to evaluate differences in associations in women who remained overweight/obese through age 45–54, who became overweight/obese by age 45–54, and who remained under-/normal weight.…”