Effects of the prolonged use of intrauterine devices (IUDs) and oral contraceptives on iron nutrition

Abstract

The effects of prolonged use of IUDs and oral contraceptives (OCs) on iron nutrition were studied in 223 women attending a family planning clinic in Talca, Chile. 100 women used Cu T 200 IUDs, 97 used OCs, and 26 controls were sterilized or used barrier methods or abstinence. The OC in all cases was Lo-Femenal, which contains 21 pills with 0.3 mg norgestrel and 0.03 mg of ethinyl estradiol, and seven pills with 75 mg of ferrous fumarate. The women ranged in age from 20 to 39 years, had one to three children, and had used their current method for three to five years. The IUD groups had a significantly lower hemoglobin level at 13.5 +or- 1.0 g/dl than the OC group at 14.2 +or- 1.0 g/dl or the control group at 14.0 +or- 1.3 g/dl. The hematocrit level was also significantly lower in the IUD than in the OC group. There were no significant differences in hemoglobin or hematocrit levels between the OC and control groups. The IUD group had an average transferrin saturation of 30.6 +or- 12.0%, significantly lower than the 34.8 +or- 10.0% of the OC group. The serum ferritin at 58.9 +or- 2.2 in the OC group was significantly higher than the 26.2 +or- 2.1 of the IUD group or the 21.1 +or- 2.4 ng/ml of the control group. Serum ferritin was positively correlated with hemoglobin in the IUD and control groups, while ferritin and transferrin saturation were positively correlated in the OC and control groups. In the IUD, OC, and control groups, respectively, the frequency of iron depletion, defined as serum ferritin lower than 12 ng/ml, was 6.3%, 0%, and 25%, while the frequency of iron deficient erythropoiesis, defined as transferrin saturation under 15%, was 7%, 3%, and 4%, and the frequency of iron deficiency anemia was 6.5%, 0%, and 8%. The results suggest that prolonged IUD use entails risk of iron depletion. Measures to improve iron nutrition among IUD users should be considered.