Nitrogen and protein composition was determined in milk from women using oral contraceptives during lactation. Total nitrogen and nonprotein nitrogen as well as lactose and the individual milk proteins lactoferrin, alpha-lactalbumin, and serum albumin were analyzed before introduction of oral contraceptives and thereafter throughout the lactation period. Twenty-four hour milk volumes were registered by weighing the infant before and after each feeding. The four oral contraceptives used consisted of different combinations of d-norgestrel, megestrolacetate, and ethinylestradiol. Significant changes were observed between groups and controls for all parameters studied. However, the changes observed were generally within the physiological variation of normal breast milk. It is suggested that the use of oral contraceptives during lactation should be limited.
PIP: The present article reports the results of an investigation on the effects of OC (oral contraception) on lactation performance and on composition of breast milk. Mothers collaborating to the study were on combined OCs or on progestin only OCs. Before and after introduction of OC, nitrogen lactose, lactogerrin, alpha-lactabbumin, and serum albumin were analyzed; milk volume was measured by weighing the infant before and after each feeding. Significant changes were found in concentration of total protein and in individual milk protein, the magnitude of changes varying between components investigated; changes in daily milk volume were also observed. The magnitude of changes were reputed to be still within the normal range, and not to be of nutritional importance. However, negative effects could be observed in marginally or severely malnourished mothers. Use of OC during lactation should be carefully considered, and, if chosen, the lowest possible dose should be given.