Abstract
Purpose
The purpose of this study is to explore the relationships between maternal hydration status and negative pregnancy outcomes using bioelectrical impedance analysis.
Methods
The participants were healthy singleton pregnant women between the 28th to 30th weeks of gestation. Data collection was conducted during prenatal visits three times: 28-30 weeks, 32-34 weeks, and 36-39 weeks. Bioelectrical impedance measurements were performed using a tetrapolar multifrequency impedance analyzer. Data regarding the results of prenatal visits and pregnancy outcomes were collected by a self-reported questionnaire and medical chart review.
Results
Initially, 30 women volunteered to participate in the longitudinal study though, one of the participants withdrew for personal reasons. Thus, data from 29 participants were analyzed.
The results of prenatal visits which relate to the impedance (Z) were maternal weight, hematocrit values, and pulse pressure. During 28-30 weeks of gestation, lower Z correlated to higher maternal weight (r=-0.415, p<0.05). For 32-34 weeks of gestation, higher Z correlated to higher hematocrit values (r=0.388, p<0.05) and higher pulse pressure (r=0.464, p<0.05).
Examining the relationship between Z and pregnancy outcomes, higher average Z was measured in the group of women who experienced inadequate uterine contractions than women who did not (N=4, p<0.05). The lower average Z was detected in women who delivered after 41 weeks of gestation (N=4, p<0.05) and in those who had episodes of higher blood pressure (130mmHg< of systolic pressure and/or 85mmHg< of diastolic pressure) 2 hours after their deliveries (N=5, p<0.01). The average Z were measured around 500Ω or 520Ω in women who did not experience those negative outcomes. Thus, there is a possibility for a range of Z for pregnant women that indicates negative pregnancy outcomes.
Conclusions
Possible correlations of impedance values with the check-up results of prenatal visits and negative pregnancy outcomes were found in this study. Also suggested is a possibility for a range of Z during pregnancy that does not lead to negative pregnancy outcomes. Further studies with more elaborate study designs and larger sample sizes are needed to verify these findings.
