RESUMO
The increase in body water during pregnancy is responsible for the largest portion of weight gain and is of interest of clinical practitioners. However, assessing changes in body fluids is not easily accomplished during pregnancy. The purpose of this study was to examine the accuracy of bioelectrical impedance spectroscopy for estimating fluid volumes before, during, and after pregnancy. Ten healthy adult women were recruited for the study. Total body water (TBW) and extracellular fluid (ECF) volume were measured at baseline (preconception); 8-10, 24-26, and 34-36 wk of gestation; and 4-6 wk postpartum by deuterium oxide and NaBr dilution, respectively. Estimates of TBW and ECF were also obtained by bioimpedance spectroscopy (BIS). At baseline, mean values for dilution and BIS estimates of TBW and ECF were 33.2 +/- 4.6 (SD) vs. 31.6 +/- 6.2 liters and 15.2 +/- 1.3 vs. 16.9 +/- 2.3 liters, respectively. TBW and ECF estimated by BIS were not significantly different from the dilution values at any time point. These results suggest that BIS may be useful in estimating volumes of ECF and TBW during pregnancy.
Assuntos
Água Corporal/metabolismo , Espaço Extracelular/metabolismo , Gravidez/metabolismo , Adulto , Óxido de Deutério , Impedância Elétrica , Feminino , Humanos , Técnicas de Diluição do Indicador , Modelos BiológicosRESUMO
Additional energy requirements for term pregnancies are traditionally estimated as 1200 kJ/d or 325 MJ. These estimates approximate measured energy costs for well-nourished women, but non-Western populations subsisting on limited diets have much lower expenditures. Based on recent studies of energy expenditure during pregnancy, this paper reviews the 1) association between gestational weight gain and fat gain, 2) the influence of maternal energy status on basal metabolic energy expenditure in late pregnancy, and 3) potential energy metabolism adaptations available to pregnant women and how adaptations vary with energy status. Available data suggest that additional energy requirements during pregnancy vary from 0 to 500 MJ and depend on maternal energy status. If energy supplies are limited, adaptations spare energy for fetal growth; if energy is abundant, energy balance may be achieved in different ways depending on individual behavioral changes in food intake or activity patterns and on adjustments in basal metabolism or fat deposition.
