Abstract: ObjectiveTo investigate the influence of the nounal pregnant woman's pre-pregnancy body mass index (BMI) and gestational weight gain on the health of mother and infant.MethodsThree hundreds and sixty cases of monomoiphic priniparas were selected and divided according to the pre-pregnancy BMI and the gestational weight gain into groups of no more than 10, 10-15, 15.5-20,20.5-25kg, and more than 25.5kg A 11 their pregnancy outcomes were followed up.ResultsThe cesarean section rate and neonatal weight of the pre-pregnancy obesity group had no difference compared with the pre-pregnancy noun alweight group(P>0.05).The occurrence rate of pregnancy induced hypertension and gestational diabetes mellitus of the pre-pregnancy obesity group and the group with pregnancy weight gain was more than 15.5kg showed significant increase(P<0.O5).The cesarean section rate of pregnant women with gestational weight gain more than 10.Skg showed an evident increase among the obesity group (P<0.O5).The cesarean sectionmte of those with pregnancy weight gain more than 20.Skg had an evident increase in the nounal group(P<0.05).The gestational weight gain was not related to the neonatal weight(P>0.05).ConclusionThe pre-pregnancy body mass index is a risk factor for the occurrence of pregnancy complications.Excess gestational weight gain is related to pregnancy outcoma and reasonable diet control during pregnancy can not influence the neonatal weight.