It is known that prenatal alcohol and nicotine exposure are associated with reduced cognition in children. A new study published in Pediatrics examined whether drinking or smoking while breastfeeding lowers childrens cognitive scores. In this study, data were derived from The Longitudinal Study of Australian Children, which had recruited 5,107 Australian infants in 2004 who were assessed every 2 years. Relationships between drinking and smoking habits of breastfeeding mothers and childrens cognition scores were analyzed. The findings showed that an increased or riskier wave-1 maternal alcohol consumption was associated with reductions in Matrix Reasoning scores in children, 6-7 years old, who had been breastfed. Whereas, this relationship was not noted in infants who had never been breastfed. Furthermore, smoking during lactation was not associated with any outcome variable. Hence, it was inferred that exposing infants to alcohol through breastmilk may cause dose-dependent reductions in their cognitive abilities. This reduction was observed between 6 and 7 years of age, but was not sustained at age 10 to 11 years. It was stated that this relationship may be clinically significant when mothers consume alcohol regularly or binge drink during the breastfeeding phase.