Abstract
Purpose
To explore how maternal hydration status relates to negative pregnancy outcomes that includes preterm labor, pregnancy induced hypertension, and low birth weight using bioelectrical impedance analysis based on path analysis.
Methods
Participants were healthy women with a singleton pregnancy between 26 and 29 weeks of gestation. During two prenatal visits at 26-29 weeks and 34-36 weeks, clinical data were collected by self-reported questionnaire and medical chart review. In addition, bioelectrical impedance measurements were performed using a tetrapolar multifrequency impedance analyzer. Data on pregnancy outcomes were collected by self-report questionnaire and medical chart review. The relations among the variables are discussed, using path analysis.
Results
Data from 332 of 340 participants were analyzed. Negative pregnancy outcomes that correlated with significant differences in mean bioimpedance values were "preterm labor and suspected preterm labor" (SPTL) (p<0.01), "elevated blood pressure after measurement at 34-36 weeks of gestation until delivery" (EBP) (P<0.05), and "low birth weight" (LBW) (p<0.01). Higher resistance (R) values, suggestive of lower hydration status, were found in the SPTL and LBW groups, and lower R values, suggestive of higher hydration status, were found in the EBP group. In the path analysis, statistically significant paths were drawn from R or hemoglobin level to each of the three negative pregnancy outcomes. The results suggest that lower body water and/or plasma volume were related to SPTL or LBW, and that higher body water and lower plasma volume were related to EBP.
Conclusions
Possible correlations were found between bioimpedance values and negative pregnancy outcomes, mediated by maternal hydration status. However, combinations of indices for assessing the risks of negative pregnancy outcomes were not identified. Further studies are needed to identify indices for evaluating maternal hydration status leading to healthy pregnancy outcomes taking into consideration women's lifestyles and possible future clinical implications.
