Summary

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), w = 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 150mg)), 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.