Objective: Our purpose was to evaluate the interactions between fetal gender and recognized risk factors of fetal growth retardation.
Study design: 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.
Results: 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.
Conclusion: Fetal gender can affect the magnitude of the classic risk factors for fetal growth retardation.