Folate intake and ovarian reserve among women attending a fertility center

OBJECTIVE: To examine the association between dietary folate intake and antral follicle count (AFC) among women seeing treatment for infertility. DESIGN: Cohort study SETTING: Academic fertility center PATIENTS: 552 women attending the Massachusetts General Hospital Fertility Center (2007-2019) who participated in the Environment and Reproductive Health Study. INTERVENTION(S): None. Folate intake was measured using a validated food frequency questionnaire at study entry. Multivariable Poisson regression models with robust standard errors were used to estimate the association of folate intake with AFC adjusting for calorie intake, age, BMI, physical activity, education, smoking status, year of AFC, and intakes of vitamin B12, iron, and vitamin D. Non-linearity was assessed with restricted cubic splines. MAIN OUTCOME MEASURES: AFC as measured with transvaginal ultrasonography as part of routine care. RESULTS: Among the 552 women (median age 35.0 years, median folate intake 1,005 μg/day), total and supplemental folate intake had a significant non-linear relationship with AFC (P for non-linearity 0.05 and 0.02, respectively). There was a positive linear association with AFC up to approximately 1200 μg/day for total folate intake and up to 800 μg/day for supplemental folate intake; however, there was no additional benefit of higher folate intakes. The magnitude of association was modest – for example, the predicted adjusted difference in AFC between a woman consuming 400 versus 800 μg/day of supplemental folate was approximately 1.5 follicles. CONCLUSIONS: Higher intake of folate, particularly from supplements, was associated with modestly higher ovarian reserve as measured by AFC among women attending a fertility center. TRIAL REGISTRATION NUMBER: This trial was registered at clinicaltrials.gov as NCT00011713