Adult adiposity and risk of early menopause.
Level 3 - non-randomized controlled study
Prospective cohort study
PubMed 29087465 · doi:10.1093/humrep/dex304
What was done
This prospective cohort study analyzed 78,759 premenopausal women aged 25–42 years at baseline (1989) enrolled in the Nurses' Health Study II and followed through 2011. Anthropometric measures (height, current weight, weight at ages 18 and 35), weight cycling, menopausal status, and lifestyle factors were updated via biennial questionnaires. Multivariable logistic regression was used to calculate odds ratios for early natural menopause (menopause occurring before age 45) according to body mass index (BMI) categories and adiposity trajectories.
What was found
A total of 2,804 participants reported early natural menopause during follow-up. BMI demonstrated a non-linear association with early menopause. Compared with women of lean-normal weight (BMI 18.5–22.4 kg/m²), underweight women (BMI < 18.5 kg/m²) had a significant 30% higher odds of early menopause (95% CI: 1.08, 1.57). Conversely, overweight women (BMI 25.0–29.9 kg/m²) had 21% to 30% significantly lower odds. Severe obesity (BMI ≥ 35.0 kg/m²) showed no significant association in fully adjusted analyses. Underweight status at age 18 and age 35 was also associated with increased risk, with the highest odds observed among women who had a BMI < 18.5 kg/m² at age 18 combined with severe weight cycling.
Why it matters
These findings suggest that low adiposity across early and mid-adulthood is a potential risk factor for early ovarian decline, helping clarify how body composition relates to reproductive lifespan.
Limits
Adiposity measures and menopausal status were self-reported via questionnaires rather than clinically measured. Underweight women may have been misclassified with early menopause due to low-weight-induced hypothalamic amenorrhea rather than true ovarian senescence. The cohort consisted primarily of US female nurses, which may limit generalizability to other racial and socioeconomic populations.
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