INTERACTION BETWEEN FETAL GENDER AND RISK-FACTORS FOR FETAL GROWTH-RETARDATION

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/m(2)) 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.