When a breastfeeding mother smokes more than twenty to thirty cigarettes a day, the risks increase. Heavy smoking can reduce a mother's milk supply and on rare occasions has caused symptoms in the breastfeeding baby such as nausea, vomiting, abdominal cramps, and diarrhea. By keeping smoking to a minimum, a mother can decrease the risk. When a mother smokes a cigarette, the nicotine levels in her blood and milk first increase and then decrease over time. For this reason, a mother should avoid smoking just before and certainly during a feeding.
Smoking also lowers prolactin levels in the blood.
Mothers who smoke also have slightly higher metabolic rates and may be leaner than non-smoking mothers, therefore, caloric stores for lactation may be low and the mother may need to eat more. Smoking has been linked to fussiness. However the baby is fed, parents should avoid exposing him to second-hand smoke by smoking in another room or preferably outside the house. Researchers have documented the health hazards to children when one or both parents smoke. These increased risks are present in both breastfed and bottle-fed infants.