Effects of contraceptives on hemoglobin and ferritin. Task Force for Epidemiological Research on Reproductive Health, United Nations Development Programme/United Nations Population Fund/World Health Organization/World Bank Special Programme of Research, Development and Research Training in Human Reproduction, World Health Organization, Geneva, Switzerland.

The effects of combined oral contraceptives (OC), depot medroxyprogesterone acetate injections (DMPA), levonorgestrel subdermal implant (Norplant), copper-containing intrauterine devices (copper IUD), and Chinese stainless steel ring IUD on hemoglobin and ferritin were studied in 18-40-year-old, nonpregnant, and nonlactating women in seven countries (Bangladesh, Chile, China, the Dominican Republic, Pakistan, Thailand, and Tunisia). Data from 2507 women were analyzed. The study had a cross-sectional component in which 1295 current users of the contraceptive methods were compared with 1212 women initiating use of contraceptives. The results of this component showed that the current users of hormonal contraceptive methods generally had higher hemoglobin and ferritin levels than the noncontraceptors. The differences between women using hormonal contraceptive and noncontraceptors in mean values for hemoglobin varied between 3 and 6 g/L and for ferritin between 2 and 18 g/L. The current users of copper IUD had higher hemoglobin levels (difference in mean levels of 3 g/L), but lower ferritin levels (difference of 10 g/L) than noncontraceptors. Current use of the stainless steel ring had an adverse effect on both hemoglobin and ferritin. In a longitudinal component of the study, 285 anemic women (hemoglobin between 80 and 120 g/L at the time of initiation of contraception)--a subgroup of the cross-sectional component--were followed-up at 3, 6, and 12 months after initiation. In this component, significant mean increases of hemoglobin at 12 months were observed among the users of oral contraceptives and DMPA, but not among users of copper or stainless steel ring IUD. It is concluded that hemoglobin and ferritin levels are influenced by the use of contraceptives and that the hormonal contraceptives included in the present study have a beneficial effect on these parameters. The effects of copper IUD on hemoglobin and ferritin should be studied further.