Association of Fecundity With Changes in Adult Female Weight.
OBJECTIVE
To evaluate whether weight change since age 18 years, current body mass index (BMI), and BMI at age 18 years are associated with fecundity.


METHODS
Our study included 1,950 women in the Nurses' Health Study 3 (2010-2014), a prospective cohort study, currently attempting pregnancy. Height, current weight, and weight at age 18 years were self-reported on the baseline questionnaire. Every 3-6 months thereafter, women reported the current duration of their pregnancy attempt. Multivariable-accelerated failure time models were used to estimate the time ratios and 95% confidence intervals (CIs).


RESULTS
For every 5-kg increase in body weight from age 18 years, current duration of pregnancy attempt increased by 5% (95% CI 3-7%). Compared with women who maintained weight, the adjusted median current duration was 0.5 months shorter in those who lost weight, 0.3 months longer for those who gained 4-9.9 kg and 10-19.9 kg, and 1.4 months longer for those who gained 20 kg or more (P trend ≤.001). The adjusted time ratio (95% CI) for a 5-kg/m increase in current BMI was 1.08 (1.04-1.12). After multivariable adjustment (including adjustment for current BMI), being underweight at age 18 years (BMI less than 18.5) was associated with a longer current duration of pregnancy attempt compared with normal-weight women (time ratio 1.25, 95% CI 1.07-1.47); however, being overweight or obese at age 18 years was not associated with fecundity.


CONCLUSIONS
Gaining weight in adulthood, being overweight or obese in adulthood, and being underweight at age 18 years were associated with a modest reduction in fecundity.


METHODS
II.
Departments of Nutrition and Epidemiology, Harvard T. H. Chan School of Public Health, and the Channing Division of Network Medicine, Department of Medicine, the Connors Center for Women's Health and Gender Biology, Department of Medicine, and the Department of Obstetrics, Gynecology and Reproductive Biology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts.
Audrey J
AJ
Gaskins
Janet W
JW
Rich-Edwards
Stacey A
SA
Missmer
Bernard
B
Rosner
Jorge E
JE
Chavarro
D000328:Adult; D015992:Body Mass Index; D005260:Female; D006801:Humans; D007247:Infertility, Female / Q000209:etiology; D009765:Obesity / Q000150:complications; D012189:Retrospective Studies; D061685:Time-to-Pregnancy; D015430:Weight Gain