[Combined influence of preconception body mass index and gestational weight gain on fetal growth]. / Influencia combinada del índice de masa corporal pregestacional y de la ganancia de peso en el embarazo sobre el crecimiento fetal.

BACKGROUND: The Chilean Ministry of Health has been using standards for nutritional evaluation and weight gain recommendations during pregnancy in the last 25 years. In the meantime new standards have been developed. AIM: To study the combined influence of preconception maternal nutritional status and gestational weight gain, using new standards to classify those parameters, on perinatal outcomes. MATERIAL AND METHODS: A cohort of 11,465 healthy pregnant women was prospectively followed until term. Their pre-gestational nutritional status was classified using the body mass index cut-offs in use in the United States (USA). Their gestational weight gain was classified using categories proposed in a Danish study. Perinatal outcomes included were risky birth weight, i.e. < 3000 g and ≥ 4000 g, and cesarean delivery. Relative risks for those perinatal outcomes were calculated for all combined categories of pre-gestational nutritional status and gestational weight gain. RESULTS: Relative risks of almost all gestational weight gain results were statistically significant for women having a normal pre-gestational nutritional status meanwhile all of them were not significant for underweight women. Overweight and obese women had similar relative risks values as normal women. However, many of them were not significant, especially in obese women. CONCLUSIONS: There is an independent and combined influence of preconception nutritional status and gestational weight gain on perinatal outcomes, when using standards to classify those parameters developed in the USA and Denmark, respectively.

Influencia combinada del índice de masa corporal pregestacional y de la ganancia de peso en el embarazo sobre el crecimiento fetal / Combined influence of preconception body mass index and gestational weight gain on fetal growth

Background: The Chilean Ministry of Health has been using standards for nutritional evaluation and weight gain recommendations during pregnancy in the last 25 years. In the meantime new standards have been developed. Aim: To study the combined infl uence of preconception maternal nutritional status and gestational weight gain, using new standards to classify those parameters, on perinatal outcomes. Material and Meihods: A cohort of 11,465 healthy pregnant women was prospectively followed until term. Their pre-gestational nutritional status was classified using the body mass Índex cut-offs in use in the United States (USA). Their gestational weight gain was classified using categories proposed in a Danish study. Perinatal outcomes included were risky birth weight, i.e. < 3000 g and ≥ 4000 g, and cesarean delivery. Relative risks for those perinatal outcomes were calculated for all combined categories of pre-gestational nutritional status and gestational weight gain. Results: Relative risks of almost all gestational weight gain results were statistically significant for women having a normal pre-gestational nutritional status meanwhile all of them were not significant for underweight women. Overweight and obese women had similar relative risks valúes as normal women. However, many of them were not significant, especially in obese women. Conclusions: There is an independent and combined infl uence of preconception nutritional status and gestational weight gain on perinatal outcomes, when using standards to classify those parameters developed in the USA and Denmark, respectively.

Estimation of individual neonatal survival using birthweight and gestational age: a way to improve neonatal care.

The study was conducted to determine the combined effect of birthweight and gestational age at birth on neonatal mortality using individually-identified livebirths. Logistic regression was used for studying the interactive effect of birthweight and gestational age on the individual probability of neonatal death. All livebirths from Chile in 2000 were included in a linked file. Odds ratio models for birthweight and gestational age were developed for each sex. The probability of neonatal death by sex was presented using contour plots. The models were statistically significant, and odds ratios were different and non-linear for the effects of birthweight and gestational age. Contour plots of constant neonatal mortality according to birthweight and gestational age were presented; they were similar for each sex. A single graph for both sexes that estimates the survival potential of infants born too early or too small would improve neonatal care in developing countries.