BACKGROUND Selective serotonin reuptake inhibitors are currently the most widely prescribed antidepressant drugs. There are only four published studies of breast-feeding mothers and their infants in which the mothers were taking fluoxetine.
METHOD Four mothers who took fluoxetine and their breast-fed infants were studied. Samples of plasma, breast-milk and urine were taken from the mothers and of plasma and urine from infants for assays of drug and metabolite concentrations. Bayley Scales of Infant Development were repeatedly used to assess cognitive and psychomotor development of the infants.
RESULTS Fluoxetine and norfluoxetine were detected in all samples of maternal plasma (range of total concentration 138-427 ng/ml) and in breast-milk (range 39-177 ng/ml). Amounts of both fluoxetine and norfluoxetine in infants' plasma and urine were below the lower limit of detection. All infants were observed to be developing normally and showed no abnormal findings on neurological examination.
CONCLUSIONS Much larger databases are needed but these four cases do not provide any evidence to suggest that women who are maintained on therapeutic doses of fluoxetine should discontinue breast-feeding their infants if they wish to breast-feed.