A mother s smoking and her daughter s age of menarche

Another study in Human Reproduction, which examined 13,815 Danish women, reported that women who smoked for part or all of their pregnancy bore daughters began menstruating at a slightly younger age than the daughters of non-smokers.

Menarche is the age at which a girl has her first period. Early menarche has been linked to higher rates of heart disease and breast cancer, among other health risks. The study was based on women s self-reporting of whether or not they drank or smoked during pregnancy. The researchers interviewed the mothers between 1984 and 1987 and their daughters in 2005 to ask them about the timing of their first period. The difference between the time of menarche for daughters of women who smoked and those who did not was three to four months on average.

Is three to four months significant? Not to the individual certainly, but on a population-wide basis, it may well be, given the known increased risks associated with earlier menarche, ACSH's Dr. Gilbert Ross says.

ACSH's Dr. Elizabeth Whelan, however, wonders about the study s methodology. The study s authors claim that it was the norm to smoke and drink during pregnancy in the 1980s, and that they therefore trust the patient self-reporting. But I don t think it was so accepted even then.

Dr. Ross concurs with this, observing that self-reporting is subject to fudging and under-reporting. However, given the fact that 40% of the women admitted to smoking during pregnancy, the degree of under-reporting is probably small. The message from this study gives us yet another reason not to smoke during pregnancy.