Journal Article

Assessment of change in hydration in women during pregnancy and postpartum with bioelectrical impedance vectors

Hall, Clinton B., Siders, William A., Lukaski, Henry C.

2007

Overview

This study tested the hypothesis that bioelectrical impedance vectors, group and individual, are valid indicators of total body water (TBW) and hydration status in women experiencing fluid gain and loss during and after pregnancy. We measured TBW, assessed with D 2O dilution, and resistance (R) and reactance (Xc), determined with 800 μA at 50 kHz and standardized for height (H) and plotted on a bivariate (R-Xc) graph, in 15 women, 21–37 y of age, longitudinally before and during pregnancy and postpartum (PP). Body weight (61.9 ± 2.3 to 75.5 ± 2.3 kg) and TBW (31.4 ± 1.1 to 38.2 ± 1.1 L) increased ( P < 0.05) from before pregnancy to the third trimester of pregnancy and decreased PP (67.0 ± 2.3 kg and 32.7 ± 1.1 L, P < 0.05). R/H and Xc/H decreased during pregnancy ( P < 0.05, 361 ± 10 to 318 ± 10 and 44 ± 1 to 36 ± 1 ω/m, respectively) and increased PP ( P < 0.05, 355 ± 10 and 41 ± 1 Ω/m). Vector length decreased ( P < 0.05, 363 ± 10 to 320 ± 10 Ω) during pregnancy and increased PP ( P < 0.05, 357 ± 10 Ω). Changes in vector length and TBW during pregnancy and PP were correlated ( r = −0.599, P < 0.001). Women with vectors exceeding a 75% tolerance interval had greater TBW gain (10–12 versus 5–6 L) during pregnancy compared with other women with vectors within this tolerance level. These findings indicate that impedance vectors provide quantitative evidence of hydration status during pregnancy and that the impedance vector method is useful in monitoring hydration status in pregnancy.

• Publisher: Elsevier Inc,Elsevier,Elsevier Limited
• Subject: Adult / Age / bioelectrical impedance / Biological and medical sciences / Body mass index / body water / Body Water - metabolism / Body weight / Body Weight - physiology / Deuterium Oxide - metabolism / Electric Impedance / Feeding. Feeding behavior / Female / Fundamental and applied biological sciences. Psychology / Gastroenterology and Hepatology / Human / Humans / Hydration / hydration status / Hypertension / Impedance / longitudinal studies / maternal nutrition / Menstruation / nutrition assessment / postpartum period / Postpartum Period - physiology / Pregnancy / Pregnancy - physiology / pregnant women / prenatal care / Radioisotope Dilution Technique / Studies / Total body water / Urine / Validity / Vertebrates: anatomy and physiology, studies on body, several organs or systems / Water-Electrolyte Balance - physiology / Weight Gain / Women