Objective: To evaluate whether iron supplement use or greater intake of total, heme and nonheme iron is associated with lower risk of ovulatory infertility.
Methods: We conducted a prospective cohort study among 18,555 married, premenopausal women without a history of infertility who attempted a pregnancy or became pregnant between 1991 and 1999 (mean baseline age+/-standard deviation 32.6+/-3.6). Diet was assessed twice during follow-up and prospectively related to the incidence of infertility due to ovulatory disorder.
Results: During the 8 years of follow-up, 438 women reported infertility due to ovulatory disorder. Women who consumed iron supplements had a significantly lower risk of ovulatory infertility than women who did not use iron supplements (relative risk 0.60, 95% confidence interval 0.39-0.92), after adjusting for potential confounders. Total nonheme iron intake, primarily consumed as multivitamins and iron supplements, was inversely associated with the risk of infertility (relative risk Quintile 1 compared with 5, 95% confidence interval 0.39-0.92; P, trend .005.) Heme iron intake was unrelated to ovulatory infertility in multivariable adjusted analyses.
Conclusion: Consumption of iron supplements and nonheme iron from other sources may decrease the risk of ovulatory infertility.
Level of evidence: II-2.