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Encourage young mothers who quit smoking during pregnancy to maintain that smoking cessation after delivery, or at least to moderate the number of cigarettes smoked per day if they relapse, could extend the duration of lactation say the authors of a U.S. study published in the "American Journal of Public Health."

Since only a few studies have attempted to assess the association between duration of breastfeeding and smoking women before, during and after pregnancy, Dr. Jihong Liu, Centers for Disease Control and Prevention U.S. to Atlanta (Georgia), and colleagues analyzed data collected from more than 3,000 women who participated in the Oregon Pregnancy Risk Assessment Monitoring System, an inquiry set up in the state to collect information about the behavior and experiences of young mothers.

The team of U.S. researchers has found that while 91% of young mothers first started breastfeeding, 25.7% of them have stopped feeding their children in before their baby reaches the age of ten weeks.

Further analysis showed that this early weaning of the child is more common in mothers described as "persistent smokers" (women who smoked before, during and after pregnancy) and those smoking more than ten cigarettes a day after birth (whether a relapse or they have not been able to stop smoking during pregnancy).

These two groups of women appear more than two times more likely than non-smoking mothers stop breastfeeding their child before it reaches the age of ten weeks, report U.S. researchers.

In contrast, the probability of an early withdrawal of the newborn appeared similar in nonsmokers and women who finally quit smoking during pregnancy or in those who relapsed after childbirth, but nevertheless limit their consumption remain below ten cigarettes per day.

According to the authors, this reduction in the duration of lactation in women who smoke may not only be due to physiological factors already identified in previous studies (such as reduced prolactin synthesis, and thus lower milk production in smokers, for example), but also for other reasons.

Thus, a mother who smokes may cease to breastfeed because it suffers from many colic (these problems seem more common effect in children breastfed by mothers who smoke than in those fed breast or a non-smoking mother).

In view of these results, and to the extent that breastfeeding should be preferred, U.S. researchers believe that health professionals should assist and advise young mothers about smoking cessation not only before and during pregnancy, but also after delivery, so that they can breastfeed longer.