Body iron stores and patterns of bleeding after insertion of a levonorgestrel- or a copper-releasing intrauterine contraceptive device

Abstract

The effects of the use of a copper-releasing IUD (Nova-T) and a levonorgestrel-releasing IUD on iron stores were studied over the first year after postmenstrual insertion and during lactation after childbirth. The pattern of bleeding was evaluated daily over the first year. Conventional hematological evaluations and serum ferritin concentrations were measured in 15 women in each group at the time of insertion, and six and twelve months later. After postmenstrual insertion, there was a significant increase at one year in the number of red blood cells in the levonorgestrelreleasing IUD group and an increase in the mean serum ferritin concentration that was not significant. In the copper-releasing IUD group, a significant (p< 0.025) decrease was found in serum ferritin concentrations after six and twelve months and a statistically significant difference existed between serum ferritin concentrations of the copper-releasing IUD group and the levonorgestrel-releasing IUD group at one year (p< 0.02). When the IUDs were inserted puerperally, there was a significant rise in the number of red blood cells and decreases in the mean corpuscular volume and mean corpuscular hemoglobin at one year in both groups. The mean serum ferritin concentration decreased during the first six months in both groups but, in the levonorgestrel-releasing IUD group it reached a plateau and in the copper-releasing IUD group it continued to decrease. At one year there was a significant difference in the mean serum ferritin concentrations between the IUD groups (p< 0.005). The different effects of these two IUDs on body iron balance are based on differences in the patterns of bleeding in the women using the IUDs. Over the first three months of postmenstrual insertion, the number of days of bleeding and spotting was higher in the levonorgestrel-releasing IUD group than in the copper-releasing IUD group, but during the latter half of the year there were fewer days of bleeding and spotting in women using the levonorgestrel-IUD than in women using the copper-releasing IUD. The insertion of a levonorgestrel-releasing IUD during lactational amenorrhea was associated with more days of bleeding and spotting during the three first months than the insertion of a copper-releasing IUD. Most of this was scanty spotting and after the first month, the women using levonorgestrel-IUD had fewer days of menses-like bleeding than the women using a copper-releasing IUD. The results of the study show that the long-term effects of the IUDs on iron stores may be precisely evaluated by using serum ferritin determinations. The copper-releasing IUD, which results in a minimal increase in the amount of bleeding over the first year, still affects the serum ferritin concentration whereas the levonorgestrel-releasing IUD is associated with a decreased amount of bleeding and prevents consumption of the body iron stores.