Birth weight Archives - Revista Brasileira de Ginecologia e Obstetrícia
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2013;35(6):268-273
DOI 10.1590/S0100-72032013000600006
PURPOSE: To describe the anthropometric and pregnancy characteristics of women with HIV/AIDS, assisted by the Brazilian National Health System and the birth weight of their newborns. METHODS: The participants were women assisted at public STD/AIDS clinics of the Municipal Health system of São Paulo. The anthropometric characteristics were evaluated by trained nutritionists and other information was obtained from the medical records. For comparison of the survey data to those of the general population, secondary maternal and pregnancy data were obtained from live birth certificates through the Live Birth Information System. Continuous variables were summarized as mean and standard deviation or as the 25th, 50th and 75th percentiles and minimum and maximum values. The other variables are presented as percentages. Means were compared by the Student's t-test or Kruskal-Wallis test depending on the fulfillment of assumptions, with the decision based on the p value. RESULTS: We found the presence of inadequate maternal nutrition according to triceps skinfold (60.9%). The BMI/gestational age showed the presence of underweight (18.5%) and overweight or obesity (40%). There was no association between disease status (HIV or AIDS) and weight, height, and lean or fat mass. Mean newborn birth weight was lower than the value for the general population without infection or disease. The results of this study indicate the need to develop adapted curves to allow a more accurate nutritional assessment of this population group.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2013;35(6):268-273
DOI 10.1590/S0100-72032013000600006
PURPOSE: To describe the anthropometric and pregnancy characteristics of women with HIV/AIDS, assisted by the Brazilian National Health System and the birth weight of their newborns. METHODS: The participants were women assisted at public STD/AIDS clinics of the Municipal Health system of São Paulo. The anthropometric characteristics were evaluated by trained nutritionists and other information was obtained from the medical records. For comparison of the survey data to those of the general population, secondary maternal and pregnancy data were obtained from live birth certificates through the Live Birth Information System. Continuous variables were summarized as mean and standard deviation or as the 25th, 50th and 75th percentiles and minimum and maximum values. The other variables are presented as percentages. Means were compared by the Student's t-test or Kruskal-Wallis test depending on the fulfillment of assumptions, with the decision based on the p value. RESULTS: We found the presence of inadequate maternal nutrition according to triceps skinfold (60.9%). The BMI/gestational age showed the presence of underweight (18.5%) and overweight or obesity (40%). There was no association between disease status (HIV or AIDS) and weight, height, and lean or fat mass. Mean newborn birth weight was lower than the value for the general population without infection or disease. The results of this study indicate the need to develop adapted curves to allow a more accurate nutritional assessment of this population group.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2012;34(7):304-309
DOI 10.1590/S0100-72032012000700003
PURPOSE: To evaluate the impact of body mass index (BMI) at the beginning of pregnancy and weight gain on pregnancy outcome so that this measure can be implemented and valued by prenatal care health services. METHOD: Cross-sectional population-based study of all births in the only two hospitals in Rio Grande city (Brazil), in 2007. Among the 2,557 mothers interviewed, it was possible to calculate BMI in only 1,117. The Stata 11 software was used for data analysis. Logist regression was applied to the outomes involving diabetes mellitus, premature labor and cesarean section. Regarding birth weight, data were adjusted by multinomial logistic regression using as base category the group of 2,500 to 4,000 g. The level of significance was set at p-value <0.05 in a two-tailed test. RESULTS: There was no increased risk of hypertension or diabetes in patients in the different groups of BMI and weight gain. The risk of preterm delivery was evident in the group with a weight gain ≤8 kg (p<0.05). Regarding the route of delivery, it was observed that the higher the BMI in early pregnancy (p=0.001) and the greater the weight gain during pregnancy (p=0.004), the greater the risk of surgical delivery, which reached 11% in the group of obese mothers (p=0.004) and 12% in the group with a weight gain ≥17 kg (p=0.001). The weight of the newborns was influenced by BMI and weight gain, and the higher the BMI in early pregnancy and the gestational weight gain, the greater the risk of macrosomia. CONCLUSION: The monitoring of BMI and weight gain during pregnancy is a low cost and useful procedure for the establishment of nutritional interventions aimed at reducing maternal and fetal risks.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2012;34(7):304-309
DOI 10.1590/S0100-72032012000700003
PURPOSE: To evaluate the impact of body mass index (BMI) at the beginning of pregnancy and weight gain on pregnancy outcome so that this measure can be implemented and valued by prenatal care health services. METHOD: Cross-sectional population-based study of all births in the only two hospitals in Rio Grande city (Brazil), in 2007. Among the 2,557 mothers interviewed, it was possible to calculate BMI in only 1,117. The Stata 11 software was used for data analysis. Logist regression was applied to the outomes involving diabetes mellitus, premature labor and cesarean section. Regarding birth weight, data were adjusted by multinomial logistic regression using as base category the group of 2,500 to 4,000 g. The level of significance was set at p-value <0.05 in a two-tailed test. RESULTS: There was no increased risk of hypertension or diabetes in patients in the different groups of BMI and weight gain. The risk of preterm delivery was evident in the group with a weight gain ≤8 kg (p<0.05). Regarding the route of delivery, it was observed that the higher the BMI in early pregnancy (p=0.001) and the greater the weight gain during pregnancy (p=0.004), the greater the risk of surgical delivery, which reached 11% in the group of obese mothers (p=0.004) and 12% in the group with a weight gain ≥17 kg (p=0.001). The weight of the newborns was influenced by BMI and weight gain, and the higher the BMI in early pregnancy and the gestational weight gain, the greater the risk of macrosomia. CONCLUSION: The monitoring of BMI and weight gain during pregnancy is a low cost and useful procedure for the establishment of nutritional interventions aimed at reducing maternal and fetal risks.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2011;33(9):240-245
DOI 10.1590/S0100-72032011000900004
PURPOSE: To determine the accuracy of ultrasound in fetal weight estimation and to evaluate maternal and/or fetal factors that could interfere in the result. METHODS: This was a transverse prospective study, involving 106 patients, with 212 fetal weight evaluations, by two observers, within 24 h to delivery. The following parameters were measured: biparietal diameter, head circumference, abdominal circumference, and femoral length. Fetal weight was estimated using the Hadlock formula and the results were compared to birth weight. The maternal factors examined were: weight, BMI, and skin to uterus distance measured by ultrasound, and the fetal factors were: presentation, position, placental localization and thickness, fetal weight, and amniotic fluid index (AFI). RESULTS: There was good correlation between estimated fetal weight and birth weight (R=0.97). In 79.2% and in 92.4% of cases the estimated fetal weight was within 10% and 15% of birth weight, respectively. The only maternal factor that presented a positive correlation with percent error in the estimate of fetal weight was the skin to uterus distance (R³0.56). Fetal weight showed negative correlation with percent error (R>-0.36; p<0.001), with a significant tendency to overestimate fetal weight in the group of very low weight - <1000 g (p<0.05). The AFI showed a low negative correlation with percent error (R=-0.21; p<0.001) with no difference between AFI groups (p=0.516). CONCLUSION: Ultrasound presented good accuracy in the estimation of fetal weight. The error of weight estimate was directly proportional to the skin to uterus distance and inversely proportional to fetal weight. AFI did not interfere significantly in the ultrasound prediction of fetal weight.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2011;33(9):240-245
DOI 10.1590/S0100-72032011000900004
PURPOSE: To determine the accuracy of ultrasound in fetal weight estimation and to evaluate maternal and/or fetal factors that could interfere in the result. METHODS: This was a transverse prospective study, involving 106 patients, with 212 fetal weight evaluations, by two observers, within 24 h to delivery. The following parameters were measured: biparietal diameter, head circumference, abdominal circumference, and femoral length. Fetal weight was estimated using the Hadlock formula and the results were compared to birth weight. The maternal factors examined were: weight, BMI, and skin to uterus distance measured by ultrasound, and the fetal factors were: presentation, position, placental localization and thickness, fetal weight, and amniotic fluid index (AFI). RESULTS: There was good correlation between estimated fetal weight and birth weight (R=0.97). In 79.2% and in 92.4% of cases the estimated fetal weight was within 10% and 15% of birth weight, respectively. The only maternal factor that presented a positive correlation with percent error in the estimate of fetal weight was the skin to uterus distance (R³0.56). Fetal weight showed negative correlation with percent error (R>-0.36; p<0.001), with a significant tendency to overestimate fetal weight in the group of very low weight - <1000 g (p<0.05). The AFI showed a low negative correlation with percent error (R=-0.21; p<0.001) with no difference between AFI groups (p=0.516). CONCLUSION: Ultrasound presented good accuracy in the estimation of fetal weight. The error of weight estimate was directly proportional to the skin to uterus distance and inversely proportional to fetal weight. AFI did not interfere significantly in the ultrasound prediction of fetal weight.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2011;33(4):164-169
DOI 10.1590/S0100-72032011000400003
PURPOSE: to assess the validity of several fetal weight charts, commonly used in Portugal, to classify its population. METHODS: observational retrospective study. Singleton birth data was analyzed, from a two- year period (May 2008 to April 2010), from pregnancies with an ultrasound in the same institution, between the 8th and 14th gestational week. Upon data validation, percentiles for each completed gestational week were created, smoothed by a quadratic function, analyzed and compared to the tables more commonly utilized, in the institution and country, by using Z-scores, percentile comparison, sample 10th percentile detection sensibility and birthweight means comparison. RESULTS: a total of 5,378 newborns (NB) were born in the period; 2,195 (42%) NB were included, born from the 24th to 42nd gestational week, allowing statistical analysis from the 34th to the 41st week. There were differences in the mean birthweight for each gestational age, between references and with the sample, as well as between sexes. The 10th percentile from some references has shown differences ranging from -288g at 37 weeks (-11% in Lubchenco et al. data), with and +133g at 34 weeks (+7,6% with Carrascosa et al. data) compared to the values found with the sample. Differences were also found concerning the sensitivity of the identification of a sample birthweight below the 10th percentile, which was between 14.1 and 100%, depending on the reference used. DISCUSSION: the limitation of these kinds of reference values must be remembered and minimized, with the adoption of regionally or nationally produced references, contemplating other variables, such as sex, with precisely known gestation duration and with validation of the utilized references in loco.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2011;33(4):164-169
DOI 10.1590/S0100-72032011000400003
PURPOSE: to assess the validity of several fetal weight charts, commonly used in Portugal, to classify its population. METHODS: observational retrospective study. Singleton birth data was analyzed, from a two- year period (May 2008 to April 2010), from pregnancies with an ultrasound in the same institution, between the 8th and 14th gestational week. Upon data validation, percentiles for each completed gestational week were created, smoothed by a quadratic function, analyzed and compared to the tables more commonly utilized, in the institution and country, by using Z-scores, percentile comparison, sample 10th percentile detection sensibility and birthweight means comparison. RESULTS: a total of 5,378 newborns (NB) were born in the period; 2,195 (42%) NB were included, born from the 24th to 42nd gestational week, allowing statistical analysis from the 34th to the 41st week. There were differences in the mean birthweight for each gestational age, between references and with the sample, as well as between sexes. The 10th percentile from some references has shown differences ranging from -288g at 37 weeks (-11% in Lubchenco et al. data), with and +133g at 34 weeks (+7,6% with Carrascosa et al. data) compared to the values found with the sample. Differences were also found concerning the sensitivity of the identification of a sample birthweight below the 10th percentile, which was between 14.1 and 100%, depending on the reference used. DISCUSSION: the limitation of these kinds of reference values must be remembered and minimized, with the adoption of regionally or nationally produced references, contemplating other variables, such as sex, with precisely known gestation duration and with validation of the utilized references in loco.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2010;32(1):4-10
DOI 10.1590/S0100-72032010000100002
PURPOSE: to evaluate the correlation between the estimated fetal weight (EFW) by ultrasonography and the neonatal weight (NW), as well as the EFW's capacity to predict changes in NW among pregnant women in João Pessoa, Paraíba, Brazil. METHODS: a diagnostic validation study, including 122 pregnant women who have had the EFW calculated by ultrasonography up to seven days before delivery and the NW established immediately after birth, with a specific newborn's scale. The correlation between EFW and NW measurements was assessed by Pearson's correlation coefficient and by the mean difference between them. EFW and NW were classified as: low for the gestational age (LGA), adequate for the gestational age (AGA) and high for the gestational age (HGA), according to the percentiles 10 and 90 of the respective reference curves. The diagnosis of EFW deviation has been validated using the values of the Alexander's NW reference curve as gold-standard, by estimating the sensitivity, specificity, and positive and negative predictive values. RESULTS: there has been a high linear correlation between the EFW and NW (R=0.96), and the difference between them has varied from -474 g to +480 g, with an average of +3 g. Most of the highest percent weight estimate variations were between 10 and 15%. EFW has had 85.7% of sensitivity and 100% of specificity for the detection of LGA, and 100 and 77.2%, respectively, for the detection of HGA. CONCLUSIONS: EFW is able to predict NW adequately, and the reference EFW tested has had a good performance in the screening of fetal growth deviation, in the population studied.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2010;32(1):4-10
DOI 10.1590/S0100-72032010000100002
PURPOSE: to evaluate the correlation between the estimated fetal weight (EFW) by ultrasonography and the neonatal weight (NW), as well as the EFW's capacity to predict changes in NW among pregnant women in João Pessoa, Paraíba, Brazil. METHODS: a diagnostic validation study, including 122 pregnant women who have had the EFW calculated by ultrasonography up to seven days before delivery and the NW established immediately after birth, with a specific newborn's scale. The correlation between EFW and NW measurements was assessed by Pearson's correlation coefficient and by the mean difference between them. EFW and NW were classified as: low for the gestational age (LGA), adequate for the gestational age (AGA) and high for the gestational age (HGA), according to the percentiles 10 and 90 of the respective reference curves. The diagnosis of EFW deviation has been validated using the values of the Alexander's NW reference curve as gold-standard, by estimating the sensitivity, specificity, and positive and negative predictive values. RESULTS: there has been a high linear correlation between the EFW and NW (R=0.96), and the difference between them has varied from -474 g to +480 g, with an average of +3 g. Most of the highest percent weight estimate variations were between 10 and 15%. EFW has had 85.7% of sensitivity and 100% of specificity for the detection of LGA, and 100 and 77.2%, respectively, for the detection of HGA. CONCLUSIONS: EFW is able to predict NW adequately, and the reference EFW tested has had a good performance in the screening of fetal growth deviation, in the population studied.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2009;31(5):241-248
DOI 10.1590/S0100-72032009000500007
OBJECTIVE: to determine the frequency of macrosomia in babies born alive at a reference obstetric service, and its association with maternal risk factors. METHODS: a transversal descriptive study, including 551 women at puerperium, hospitalized at Instituto de Saúde Elpídio de Almeida, in Campina Grande (PB), Brazil, from August to October, 2007. Women, whose deliveries had been assisted at the institution, with babies born alive from one single gestation and approached in the first postpartum day, were included in the study. The nutritional and sociodemographic maternal characteristics were analyzed, and the ratio of macrosomia (birth weight >4.000 g) and its association with maternal variables were determined. Macrosomia was classified as symmetric or asymmetric according to Rohrer's index. Statistical analysis has been done through Epi-Info 3.5 software; the prevalence ratio (PR) and the confidence interval at 95% (CI 95%) were calculated. The research protocol was approved by the local Ethics Committee and all the participants signed the informed consent. RESULTS: the mean maternal age was 24.7 years old, and the mean gestational age was 38.6 weeks. Excessive gestational weight gain was observed in 21.3% of the pregnant women, and 2.1% of the participants had a diagnosis of diabetes mellitus (gestational or clinic). A ratio of 5.4% of macrosomic newborns was found, 60 were asymmetric. There was no significant association between macrosomia, mother's age and parity. There was an association between macrosomia and overweight/obesity in the pre-gestational period (PR=2.9; CI 95%=1.0-7.8) and at the last medical appointment (PR=4.9; CI 95%=1.9-12.5), excessive weight gain (PR = 6.9; CI 95%:2.8-16.9), clinical or gestational diabetes (PR = 8.9; CI 95%:4.1-19.4) and hypertension (PR=2.9; CI 95%=1.1-7.9). The factors that persisted significantly associated with macrosomia in the multivariate analysis were the excessive weight gain during the gestation (RR=6.9; CI 95%=2.9-16.9) and the presence of diabetes mellitus (RR=8.9, CI 95%=4.1-19.4). CONCLUSIONS: considering that excessive gestational weight gain and diabetes mellitus were the factors more strongly associated with macrosomia, it is important that precocious detection measurements and adequate follow-up of such conditions be taken, aiming at preventing unfavorable perinatal outcomes.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2009;31(5):241-248
DOI 10.1590/S0100-72032009000500007
OBJECTIVE: to determine the frequency of macrosomia in babies born alive at a reference obstetric service, and its association with maternal risk factors. METHODS: a transversal descriptive study, including 551 women at puerperium, hospitalized at Instituto de Saúde Elpídio de Almeida, in Campina Grande (PB), Brazil, from August to October, 2007. Women, whose deliveries had been assisted at the institution, with babies born alive from one single gestation and approached in the first postpartum day, were included in the study. The nutritional and sociodemographic maternal characteristics were analyzed, and the ratio of macrosomia (birth weight >4.000 g) and its association with maternal variables were determined. Macrosomia was classified as symmetric or asymmetric according to Rohrer's index. Statistical analysis has been done through Epi-Info 3.5 software; the prevalence ratio (PR) and the confidence interval at 95% (CI 95%) were calculated. The research protocol was approved by the local Ethics Committee and all the participants signed the informed consent. RESULTS: the mean maternal age was 24.7 years old, and the mean gestational age was 38.6 weeks. Excessive gestational weight gain was observed in 21.3% of the pregnant women, and 2.1% of the participants had a diagnosis of diabetes mellitus (gestational or clinic). A ratio of 5.4% of macrosomic newborns was found, 60 were asymmetric. There was no significant association between macrosomia, mother's age and parity. There was an association between macrosomia and overweight/obesity in the pre-gestational period (PR=2.9; CI 95%=1.0-7.8) and at the last medical appointment (PR=4.9; CI 95%=1.9-12.5), excessive weight gain (PR = 6.9; CI 95%:2.8-16.9), clinical or gestational diabetes (PR = 8.9; CI 95%:4.1-19.4) and hypertension (PR=2.9; CI 95%=1.1-7.9). The factors that persisted significantly associated with macrosomia in the multivariate analysis were the excessive weight gain during the gestation (RR=6.9; CI 95%=2.9-16.9) and the presence of diabetes mellitus (RR=8.9, CI 95%=4.1-19.4). CONCLUSIONS: considering that excessive gestational weight gain and diabetes mellitus were the factors more strongly associated with macrosomia, it is important that precocious detection measurements and adequate follow-up of such conditions be taken, aiming at preventing unfavorable perinatal outcomes.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2008;30(10):486-493
DOI 10.1590/S0100-72032008001000002
PURPOSE: to investigate factors accountable for macrosomia incidence in a study with mothers and progeny attended at a Basic Unity of Health in Rio de Janeiro, Brazil. METHODS: a prospective study, with 195 pairs of mothers and progeny, in which the dependent variable was macrosomia (weight at delivery >4,000 g - independent of the gestational age or of other demographic variables), and socioeconomic, previous pregnancies/gestation course, biochemical, behavioral and anthropometric, the independent variables. Statistical analysis has been done by multiple logistic regression. Relative risk (RR) values have been estimated, based on the simple form: RR=OR/ (1 - I0) + (I0 versus OR), in which I0 is the macrosomia incidence in non-exposed people. RESULTS: Macrosomia incidence was 6.7%, the highest value being found in the progeny of women >30 years old (12.8%), white (10.4%), with two or more children (16.7%), with male newborns (9.6%), with height >1,6 m (12.5%), with overweight or obesity as a nutritional pre-gestational state (13.6%), and with excessive gestational gain of weight (12.7%). The final model has shown that having two or more children (RR=3.7; CI95%=1.1-9.9), and having a male newborn (RR=7.5; CI95%=1.0-37.6) were the variables linked to the macrosomia occurrence. CONCLUSIONS: macrosomia incidence was higher than the one observed in Brazil as a whole, but inferior to the one reported in studies from developed countries. Having two or more children and a newborn male were the factors accountable for the occurrence of macrosomia.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2008;30(10):486-493
DOI 10.1590/S0100-72032008001000002
PURPOSE: to investigate factors accountable for macrosomia incidence in a study with mothers and progeny attended at a Basic Unity of Health in Rio de Janeiro, Brazil. METHODS: a prospective study, with 195 pairs of mothers and progeny, in which the dependent variable was macrosomia (weight at delivery >4,000 g - independent of the gestational age or of other demographic variables), and socioeconomic, previous pregnancies/gestation course, biochemical, behavioral and anthropometric, the independent variables. Statistical analysis has been done by multiple logistic regression. Relative risk (RR) values have been estimated, based on the simple form: RR=OR/ (1 - I0) + (I0 versus OR), in which I0 is the macrosomia incidence in non-exposed people. RESULTS: Macrosomia incidence was 6.7%, the highest value being found in the progeny of women >30 years old (12.8%), white (10.4%), with two or more children (16.7%), with male newborns (9.6%), with height >1,6 m (12.5%), with overweight or obesity as a nutritional pre-gestational state (13.6%), and with excessive gestational gain of weight (12.7%). The final model has shown that having two or more children (RR=3.7; CI95%=1.1-9.9), and having a male newborn (RR=7.5; CI95%=1.0-37.6) were the variables linked to the macrosomia occurrence. CONCLUSIONS: macrosomia incidence was higher than the one observed in Brazil as a whole, but inferior to the one reported in studies from developed countries. Having two or more children and a newborn male were the factors accountable for the occurrence of macrosomia.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2008;30(4):190-195
DOI 10.1590/S0100-72032008000400006
PURPOSE: to evaluate the accuracy of fetal upper arm volume, using three-dimensional ultrasound (3DUS), in the prediction of birth weight. METHODS: this prospective cross-sectional study involved 25 pregnancies without structural or chromosomal anomalies. Bidimensional parameters (biparietal diameter, abdominal circumference and femur length) and the 3DUS fetal upper arm volume were obtained in the last 48 hours before delivery. The multiplanar method, using multiple sequential planes with 5.0-mm intervals, was used to calculate fetal upper arm volume. Polynomial regressions were used to determine the best equation in the prediction of fetal weight. The accuracy of this new formula was compared with Shepard's and Hadlock's formulas. RESULTS: fetal upper arm volume was strongly correlated to birth weight (r=0.83; p<0.005). Linear regression was the best equation [birth weight=681.59 + 43.23 x fetal upper arm volume]. The fetal upper arm volume mean error (0 g), mean absolute error (196.6 g) and mean percent absolute error (6.5%) were lower than using Shepard's formula; however, the difference did not reach significance (p>0.05). Birth weight predicted by fetal upper arm volume had a mean error lower than Hadlock's formula, but this difference was not statistically significant (p>0.05). CONCLUSIONS: the accuracy of fetal upper arm volume obtained through 3DUS is similar to the accuracy of bidimensional ultrasound in the prediction of birth weight. These findings need to be confirmed by larger studies.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2008;30(4):190-195
DOI 10.1590/S0100-72032008000400006
PURPOSE: to evaluate the accuracy of fetal upper arm volume, using three-dimensional ultrasound (3DUS), in the prediction of birth weight. METHODS: this prospective cross-sectional study involved 25 pregnancies without structural or chromosomal anomalies. Bidimensional parameters (biparietal diameter, abdominal circumference and femur length) and the 3DUS fetal upper arm volume were obtained in the last 48 hours before delivery. The multiplanar method, using multiple sequential planes with 5.0-mm intervals, was used to calculate fetal upper arm volume. Polynomial regressions were used to determine the best equation in the prediction of fetal weight. The accuracy of this new formula was compared with Shepard's and Hadlock's formulas. RESULTS: fetal upper arm volume was strongly correlated to birth weight (r=0.83; p<0.005). Linear regression was the best equation [birth weight=681.59 + 43.23 x fetal upper arm volume]. The fetal upper arm volume mean error (0 g), mean absolute error (196.6 g) and mean percent absolute error (6.5%) were lower than using Shepard's formula; however, the difference did not reach significance (p>0.05). Birth weight predicted by fetal upper arm volume had a mean error lower than Hadlock's formula, but this difference was not statistically significant (p>0.05). CONCLUSIONS: the accuracy of fetal upper arm volume obtained through 3DUS is similar to the accuracy of bidimensional ultrasound in the prediction of birth weight. These findings need to be confirmed by larger studies.
