Tobacco and E-Cigarettes
Using tobacco or e-cigarettes while breastfeeding can allow harmful chemicals to pass from the mother to the infant through breast milk or secondhand smoke exposure. Mothers who use tobacco or e-cigarettes should be encouraged to quit; regardless, breastfeeding provides numerous health benefits and breast milk remains the recommended food for an infant.
Source: Centers for Disease Control and Prevention (2021). Tobacco and E-Cigarettes.