Hypothesis: smoking decreases breast feeding duration by suppressing prolactin secretion.

A number of studies, including new data summarized here, conclude that breast feeding duration is lower in smoking mothers. Although some have suggested that this merely reflects poor health motivation in those prone to smoke, several lines of evidence support the view that chronic smoking does indeed compromise breast feeding by suppressing prolactin secretion and thereby lowering breast milk volume. Moreover, a recent clinical trial shows that an effective smoking cessation program can boost breast feeding duration in smokers. An analysis of pertinent rodents studies suggests that chronic nicotine administration boosts dopaminergic activity in the tuberoinfundibular tract which functions to inhibit prolactin release; this increase in dopaminergic activity, in turn, may reflect a nicotine-mediated suppression of hypothalamic opioid activity.