Energy, protein, lactose and fat were studied in the milk of mothers who were using different types of contraceptives. One hundred and eleven mothers made up the following groups. C: control (barrier and natural methods, or sterilization), n = 22; combined pill: LDP (low dose pill (levonorgestrel 0.15 mg + ethinylestradiol 0.03 mg)), n = 12 and MDP (medium dose pill (levonorgestrel 0.25 mg + ethinylestradiol 0.05 mg)), n = 13; MP (minipill (norethindrone 0.35 mg)), n = 37; DMPA (injectable progesterone (depot medroxiprogesterone acetate 150 mg)), n = 17; and IUD (plastic or copper intrauterine device), n = 10. The mean stages of lactation were, respectively, 15, 17, 5, 9, 5 and 9 weeks. The mean duration of observation for the study groups ranged from 2 to 4 weeks. Milk samples were collected before and after initiation of treatment (mean = 20 days; range = 14-103 days). The stage of lactation and the interval of nursing before sampling were recorded so that statistical account could be taken of these uncontrollable sources of variability. When incorporated as covariates, they showed that no significant differences existed between the groups tested, either before or after treatment.
PIP: Researchers compared data on 22 women using either a barrier method or a natural family planning method or had undergone female sterilization (controls) with data on 89 women using either a low dose combined oral contraceptive (OC), a medium dose combined OC, a low dose progestin only OC, the injectable Depo-Provera, or an IUD to examine the hormonal contraceptives' effects on the concentration of total protein, lipids, lactose, and energy in human milk. They recruited the women from private and public family planning clinics in Brasilia, Brazil between 1984 and 1987. The mean stages of lactation were 15 weeks for controls, 17 weeks for women using the combined low dose OC, 5 weeks for those using the combined medium dose OC, 5 weeks for those using the combined medium dose OC, 9 weeks for those using the low dose progestin only OC, 5 weeks for those using Depo-Provera, and 9 weeks for those using the IUD. Almost all the concentrations of total protein, lipids, lactose, and energy both before and after contraceptive therapy fell within the range for healthy women. The mean value of total protein in women using Depo-Provera was the only value higher than that range. The low dose OC was associated with a considerable increase in fat (3 g/dL vs. 4.8 g/dL; p=.035). Women taking the medium dose OC experienced a significant decrease in lactose (6.8 g/dL vs. 7.25 g.dL; p=.004). The time between last nursing and milk sample collection (nursing interval) caused considerable variation in fat (p=.03) and total energy (p=.02) in those samples collected before contraceptive therapy. When the researchers adjusted the data for stage of lactation and nursing interval from all 6 groups, the contraceptives had no significant effect on total protein, lipids, lactose, and energy.