Effects of hormonal contraceptives on milk volume and infant growth who special program of research development and research training in human reproduction
Et Al
Contraception 30(6): 505-522
1984
ISSN/ISBN: 0010-7824 Document Number: 562970
WHO conduced a 3-center study in Hungary and Thiland to evaluate the effects of homonal contraception on lactation and infant growth. Women choosing oral contraceptives were randomly assigned to a combined oral contraceptive containing 30 .mu.g ethinyl estradiol and 150 .mu.g levonorgestrel (N - 86) or a progestin-only preparation containing 75 .mu.g dl-norgestrel (N = 85). Identical packaging and treatment schedules allowed double-blind observation. Women (11) using no contraception or non-hormonal methods acted as controls. In the 2 Thai centers 59 women using depot-medroxyprogesterone acetate formed an additional comparison group. All subjects were healthy women with normal deliveries, whose infants had normal birth weights and satisfactory growth in the neonatal period. Breast milk vol was determined by pump expression using standardized procedures. Information was obtained on nursing frequency and supplementation, infant growth and morbidity. Pretreatment observations at 6 wk post-partum were used as a baseline, and subjects were followed-up at 9, 12, 16 20 and 24 wk post-partum. Women using combined oral contraceptives had a decline in milk vol within 6 wk of initiating treatment; no significant decrease was observed in the other treatment groups. After 18 wk of treatment, combined oral contraceptive users experienced a 41.9% decline in milk vol, compared to 12.0% with progestin-only minipills and 6.1% in the non-hormonal controls. The prevalence of complementary feeding and withdrawals due to inadequate milk supply were comparable in the 4 treatment groups. Data were not available on the daily amounts of complementary feeds. There were no significant differences in growth of infants between treatment groups. Women may have compensated for declines in milk vol by more supplementary feeding or by more prolonged and intense suckling episodes. The 30 .mu.g estrogen-containing combined oral contraceptives impair milk secretion, but in the selected healthy group of mothers and children studied with the prevailing level of supplementary feeding, this did not adversely affect infant growth.