Abstract: This study sought to estimate the prevalence of maternal smoking and its association with exclusive breastfeeding vs. formula feeding. A cross-sectional study was performed on postpartum women at a public hospital in Spain, between January and August 2018. The main variables studied were their age, level of study, smoking habits, and chosen mode of infant feeding. In total, 948 postpartum women were included. Of these, 12.45% were smokers who smoked a mean of 7.23 cigarettes/day. Among the group of smokers, the probability of feeding the newborns with formula milk was multiplied by 2.32 ([95%CI 1.50-3.58] p < 0.001). When stratifying tobacco use into mild, moderate and severe, we found a statistically significant dose-response pattern. These associations and their statistical significance were maintained when adjusting by age and level of study. In conclusion, in the group of postpartum mothers who smoked, the probability of feeding the newborns with formula milk doubled. Our data highlight the need to improve health education programs in women of childbearing age, especially during pregnancy.
