Objective: The purpose of this study was to determine whether hypotonic dysfunctional labor is associated with hypophosphatemia.
Study design: We conducted a prospective nested case control study of term women who were in active labor. Serum phosphate samples were drawn at admission with active labor and before delivery. Phosphate concentration was compared between control subjects and women with hypotonic, dysfunctional uterine contractions.
Results: Both serum samples were available for 90 women. Hypophosphatemia was documented in 14% of the participants. There was no significant difference in phosphate concentration between the 2 groups either at admission or before delivery. The mean decrease in phosphate concentration between admission and delivery was similar between the 2 cohorts.
Conclusion: Although transient hypophosphatemia is found commonly in laboring women, hypotonic dysfunctional contractions are not associated with mild hypophosphatemia.