摘要Objective To determine the concentration changes of medroxyprogesterone acetate (MPA) in serum and milk in the Chinese lactating women who used Depo Geston Methods Ten postpartum and breastfeeding women received an injectable contraceptive of Depo Geston (depo medroxyprogesterone acetate, DMPA, 150 mg/ampoule). Serum and milk samples were collected in the 1st, 2nd, 4th, 6th, 8th 10th and 12th week after contraceptive injection. The concentrations of medroxyprogesterone acetate (MPA) in serum and milk were determined by radioimmunoassay.Results The highest MPA concentration in serum was observed at the 1st week and then the level of serum MPA decreased obviously at the 2nd and 4th week. After the 4th week, the decline of serum MPA level slowed down. The concentration of milk MPA reached the highest level at 1st week. But at the 2nd week the average level of MPA in milk dropped by half The MPA concentration in the milk was changed in the range of 5.2 -8.3 ng/mL in the following 10 weeks. During observation, the average ratios of concentration and area under curve (AUC) in milk/serum were both 0.55. There was a wide variation in MPA concentrations and ratios of milk/serum between subjects.Conclusion MPA concentrations maintained a certaim level at the 12th week after DMPA injection. However, whether mather's intake of DMPA during feeding period has effect on children 's growth, espcially pubertal growth, deserves further studies.