Is being childless associated with a woman's risk of overweight and obesity? Results from a national longitudinal study.

Abstract

To examine the association between motherhood status (mothers, voluntarily childless, involuntarily childless) and overweight and obesity over 22 years. A total of 4092 women aged 18-23 years were followed from 1996 to 2018. Motherhood status was defined by women's reports on their fertility, attempts to conceive, use of in vitro fertilisation and fertility hormones, and number of biological children. Associations between motherhood status and overweight and obesity were examined using generalised estimating equations models, adjusting for socio-demographic characteristics, lifestyle factors, depressive symptoms, early life factors, and polycystic ovary syndrome (PCOS). At age 40-45 years, 12% of women were voluntarily childless and 5% were involuntarily childless. The prevalence of overweight and obesity increased with age and women who were voluntarily or involuntarily childless had higher prevalence of obesity than mothers in all surveys. After adjusting for covariates, compared with mothers, women who were voluntarily childless had higher odds of being overweight (odds ratio [OR], 95% confidence interval [CI]: 1.29, 1.09-1.52) and obese (OR, 95% CI: 1.65, 1.29-2.12). Involuntary childlessness was not associated with being overweight (OR, 95% CI: 1.05, 0.82-1.33), and its association with obesity was attenuated after adjusting for PCOS in the final model (OR, 95% CI: 1.40, 0.99-1.98). Around one in nine Australian women remained voluntarily childless by their late reproductive years. On average, they had higher odds of being overweight and obese than mothers, suggesting that overweight and obesity prevention programs should consider tailoring their advice by motherhood status.