Are Women With Threatened Preterm Labor More Dehydrated Than Women Without It?

OBJECTIVE: To determine if women who present to the labor and delivery unit at 23 0/7 to 36 6/7 weeks gestation with threatened preterm labor (TPTL) are more likely to be dehydrated than women who present at the same gestational age for other reasons.

DESIGN: Retrospective cohort study.

SETTING: An academic medical center in the northeastern United States.

PARTICIPANTS: All women at preterm gestational ages 23 0/7 to 36 6/7 weeks who presented to the labor and delivery unit for care in 2014.

METHODS: We compared hydration status by urine specific gravity of women with TPTL to that of women with other chief complaints. Women for whom data were missing and those with hypertension, diabetes, renal disease, vaginal bleeding, ruptured membranes, advanced dilation (>3 cm), multiple gestation, or fetal demise were excluded. Chi-square statistic and a receiver operating characteristic (ROC) curve were used for data analysis.

RESULTS: A total of 840 women at 23 0/7 to 36 6/7 weeks gestation presented during the study period; 188 of these had TPTL, 261 had other chief complaints, and 391 were excluded. The proportion of women diagnosed with dehydration was similar between those with TPTL (39%) and those with other complaints (46%, p = .12). An ROC curve showed no association between TPTL and hydration status (area under the curve = 0.57, 95% confidence interval [0.46, 0.67]).

CONCLUSION: At 23 0/7 to 36 6/7 weeks gestation, the hydration status of women with TPTL was not different from those without TPTL. Because there is no relationship, it is unlikely that hydration is a worthwhile therapy for women with TPTL, although additional prospective study is warranted.