PIP: Levels of contraceptive steroids in breast milk and plasma of lactating women were investigated. 7 lactating women received 150 mg medroxyprogesterone acetate (MPA) 1 week after delivery. 5 women (lactating) took 350 mcg norethisterone (NET) and 2 took 150 mcg d-norgestrel (d-ng) + 30 mcg ethinyl estradiol. Milk and blood samples were drawn and radioimmunoassay of the contraceptive drug levels were performed. In all 7 women taking MPA, drug was detected in the breast milk and plasma in a ratio of 1:1 for a period of 87 days. NET was also present in milk and plasma but the concentration in milk was about 1/10 of the amount in plasma. d-Ng levels were also less than 1/10 that in plasma.