Duration of breast-feeding and development of children after insertion of a levonorgestrel-releasing intrauterine contraceptive device.

IUDs releasing levonorgestrel, 10 micrograms per day (30 patients) and 30 micrograms per day (40 patients), and copper-releasing IUDs (Nova-T) (40 patients) were inserted six weeks after delivery in 110 breast-feeding amenorrheic women. The infants were carefully followed-up by recording monthly weight gain and growth, age of eruption of the first tooth, age of being able to walk without support and morbidity to infective diseases. No differences were noticed between the study groups. Plasma samples were collected from 13 children at the age of eight months, while the mothers were breast-feeding. Six mothers had a levonorgestrel-releasing IUD and seven others the Nova-T or no hormonal or intrauterine contraceptive. No differences were noticed between the groups in Na, K, Cl, Ca, P, protein, albumin, creatinine, urate, Fe, cholesterol, triglyceride, bilirubin, alkaline phosphatase, aspargine aminotransferase, alanine aminotransferase, lactate-dehydrogenase or high density lipoprotein cholesterol serum concentrations in the children. The duration of breast-feeding and initiation of supplementary feeding was recorded. The continuation of breast-feeding 75 days after the insertion of a 30-micrograms per day levonorgestrel-releasing IUD was 56 percent while in the Nova-T group only 21 percent had discontinued which is a statistically significant difference (p less than 0.05); later the difference disappeared. Compared with the lactation time of their previous breast-feeding reported by women in both groups, the present lactation time increased by ten weeks. The infants received substitute foods including substitute milk, juices, etc., in the Nova-T group at 3.9 months and in the levonorgestrel-releasing IUD group at 3.4 months after delivery.