[Maternal factors associated with fetal weight estimated by ultrasonography]

to evaluate the effect of maternal, socioeconomic and obstetric variables, as well the presence of artery incisions in the 20th and 24th weeks on the fetal weight estimated at the end of pregnancy (36th week) in pregnant women attended by Programa Saúde da Família, in an inland town of the northeast of Brazil.

a longitudinal study including 137 pregnant women, who have been followed up every four weeks in order to assess clinical, socioeconomic and obstetric conditions, including their weight. The uterine arteries were evaluated by Doppler in the 20th and 24th weeks, the fetal weight and the amniotic fluid index (AFI), determined in the 36th week. The initial maternal nutritional state has been determined by the body mass index (BMI), the pregnant women being classified as low weight, eutrophic, over weight and obese. Weight gain during gestation has been evaluated, according to the initial nutritional state, being classified at the end of the second and third trimester as insufficient, adequate and excessive weight gain. Analysis of variance was performed to evaluate the association of the fetal weight in the 36th week with the predictor variables, adjusted by multiple linear regression.

an association between the fetal weight estimated in the 36th week and the mother's age (p=0.02), mother's job (p=0.02), initial nutritional state (p=0.04), weight gain in the second trimester (p=0.01), presence of incisions in the uterine arteries (p=0.02), and AFI (p=0.007) has been observed. The main factors associated to the fetal weight estimated in the 36th week, after the multiple regression analysis were: BMI at the pregnancy onset, weight gain in the second trimester, AFI and tabagism.

in the present study, the fetal weight is positively associated with the initial maternal nutritional state, the weight gain in the second trimester and the volume of amniotic fluid, and negatively, to tabagism.