Washington, DC -- Women who took iron supplements had nearly half the risk of developing ovulatory infertility compared with women who did not use iron supplements, according to a new study in the November issue of Obstetrics & Gynecology. Women taking supplements with high iron content (41 mg or more) had an even lower risk (62%) of ovulatory infertility compared with women who took no supplements, according to this study. Similarly, women consuming high amounts of iron from other non-animal sources had a significantly lower risk of ovulatory infertility compared with women who consumed little iron in their diet.

According to the researchers, iron deficiency is the most prevalent nutritional deficiency worldwide. Women of childbearing age in the US are at increased risk of this condition. Menstruation can lead to iron deficiency, as can pregnancy and lactation because both demand more iron.

Harvard researchers reviewed data from the Nurses' Health Study II on more than 18,500 married, premenopausal women without a history of infertility who either attempted a pregnancy or became pregnant between 1991 and 1999. The Nurses' Health Study II is a prospective study of more than 116,000 female registered nurses ages 24 to 42 funded by the National Institutes of Health.

The researchers say that because this is the first study reporting a possible association between iron and ovulatory infertility, it is important that more randomized trials be done. They point to a previous small clinical trial testing the efficacy of an iron-containing supplement among women who had unsuccessfully tried to get pregnant that documented a higher pregnancy rate in the treatment group. They suggest that women planning to become pregnant should consider using iron supplements because it may help prevent iron deficiency and improve fertility.

Contact: Robin Herman, Assistant Dean for Communications, Harvard School of Public Health, at 617-432-4752 or rherman@hsph.harvard.edu.

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