title: Levonorgestrel concentrations in maternal and infant serum during use of subdermal levonorgestrel contraceptive implants, Norplant, by nursing mothers.
abstract: The transfer of levonorgestrel to infants was studied in 42 lactating women in whom the contraceptive subdermal implants, Norplant, were inserted 30 to 40 days postpartum. The women breastfed their infants for one year. Simultaneous mother and infant blood samples were taken once during the year. The levonorgestrel serum concentrations were measured by radioimmunoassay. During the first postinsertion month, the levonorgestrel concentration in the infants serum amounted, on the average, to 5% of the maternal concentration. Thereafter, the ratio ranged from 8 to 13%. The implications of this finding are discussed.
mesh_terms: D001942:Breast Feeding; D004343:Drug Implants; D005260:Female; D006801:Humans; D007223:Infant; D016912:Levonorgestrel; D009644:Norgestrel / Q000008:administration & dosage / Q000097:blood*
chemical_list: D004343:Drug Implants; D009644:Norgestrel; D016912:Levonorgestrel