Interaction between fetal gender and risk factors for fetal growth retardation.

Abstract

Our purpose was to evaluate the interactions between fetal gender and recognized risk factors of fetal growth retardation. A case-control study of 530 singleton pregnancies complicated by fetal growth retardation and 782 control pregnancies with appropriately grown fetuses was conducted. Interactions were evaluated by logistic regression analysis. In logistic regression analysis fetal growth retardation was more frequent in female than male fetuses (odds ratio 1.39, 95% confidence interval 1.06 to 1.82). In female fetuses hypertension-related fetal growth retardation was three times more common than in males. On the other hand, a low (< 50 kg) maternal prepregnancy weight and a low (< 18) body mass index (kg/m2) were significant risk factors for fetal growth retardation in male fetuses only. Although maternal smoking in pregnancy was a significant risk factor for growth retardation in both male and female fetuses, its effect was significantly stronger in male fetuses. Fetal gender can affect the magnitude of the classic risk factors for fetal growth retardation.