Fetal Sex Plays Role in Moms' Asthma

A baby?s gender may affect asthma symptoms in pregnant women. For the study, researchers monitored 702 pregnant women in southern New England and collected data on lung function and other factors that may impact the severity of the women?s asthma.

The results of the study showed that asthma symptoms worsened in women with either male or female fetuses until about 30 weeks? gestation. After that time frame, mothers showed improvement in lung function. Throughout pregnancy, however, women carrying male fetuses had about 10% better lung function, compared with women carrying female fetuses.

Reporting in the American Journal of Epidemiology (February 1, 2006), the researchers suggested that testosterone secreted by the male fetus may relax the mother?s bronchial tissues and hold back the response to histamines. On the flip side, certain sex-specific chemicals excreted by female fetuses may exacerbate inflammation in pregnant women.