OBJECTIVE:The present study examined whether ethanol exposure influences lactation parameters. Specifically, selected constituents in maternal blood and milk and the lactation performance of Chinese lactating mothers were evaluated after they had consumed chicken soup flavoured with sesame oil and rice wine (CSSR), a diet traditionally prescribed during the postpartum 'doing-the-month' ritual. DESIGN:Twenty-three lactating mothers were examined. Informed consent was obtained from each subject. Each subject was tested on two occasions separated by a week. The target alcohol dosage was 0.3 g/kg body weight. Milk and blood samples were collected prior to consumption of soup and at 120 and 150 min, respectively, after consumption. Levels of various constituents were measured. The time for ejection of the first milk droplet and total milk volume yielded were also measured. RESULTS:Consumption of CSSR influenced TAG, insulin and lactate levels in maternal blood. Likewise, consumption of the soup affected milk composition and its nutritional status, particularly total protein, TAG, fatty acid, beta-hydroxybutyrate and lactate levels. CSSR intake significantly affected TAG and lactate levels in milk. The time for the first milk droplet to be ejected was significantly longer in the CSSR group, indicating that the milk-ejecting reflex is inhibited. However, blood prolactin level increased slightly after ethanol intake. Milk yields were reduced after ingestion of CSSR although the difference was not statistically significant. CONCLUSION:Consumption of CSSR affects not only the composition of maternal blood and milk, but also lactation performance. These findings suggest that an alcoholic diet should be avoided during lactation.