Maternal smoking decreases antioxidative status of human breast milk.

Objective: To evaluate the influence of maternal smoking on antioxidative capacity and intensity of oxidative damage in breast milk.

Study Design: The study group (n=30) was comprised of postpartum women who declared smoking more than five cigarettes per day during pregnancy and lactation (confirmed by the urinalysis of cotinine concentration), and their newborns. Control group included 29 non-smoking postpartum women and their newborns. Colostrum samples were collected on the 3rd day after delivery and breast milk samples between the 30th and the 32nd day after delivery. Morning maternal and neonatal urine samples were obtained on the day of the mature milk sampling. Isoprostane concentrations in colostrum/mature milk and urine were determined immunoenzymatically. Total Antioxidant Status (TAS) of colostrum/breast milk was determined by Rice-Evans and Miller method.

Result: Colostrum TAS in smokers was significantly lower than in non-smokers (P=0.006). In both groups, the TAS of mature milk was higher compared with colostrum, but significant differences were observed amongst smokers only (P=0.001). In smokers the isoprostane concentration of mature milk was significantly higher than the colostrum concentration (P=0.001). Significant inverse correlation between maternal urinary isoprostane concentration and the TAS of mature breast milk was observed in smokers (R=-0.525, P=0.023), but not in non-smokers (R=0.161, P=0.422).

Conclusion: This study revealed that maternal smoking triggers harmful effects on an infant by impairing pro-oxidant-antioxidant balance of breast milk.