Abstract
Objective
To evaluate the association between maternal body mass index (BMI) and plasma oxytocin (OT) levels at different OT infusion rates in labor.
Methods
A prospective observational study analyzing serial plasma samples in laboring women with OT infusion. The women were categorized into three groups, women with non-obesity (BMI 18.5–29.9, n = 12), obesity (BMI 30.0–34.9, n = 13), and morbid obesity (BMI ≥ 35.0, n = 15). Plasma OT was analyzed using tandem mass spectrometry.
Results
Except for a low positive correlation between OT levels and BMI and significantly increased plasma OT levels in women with morbid obesity at the OT infusion rate of 3.3 mU/min, no significant differences in OT levels between the BMI groups were found. Further, the inter-individual differences in OT levels were large and no dose-dependent increase of OT levels was seen.
Conclusions
Other factors than plasma OT levels may be more likely to determine the clinical response of OT infusion in women with obesity. Perhaps the observed clinical need and individual response would be a better predictor of plasma OT levels than a pre-determined OT infusion rate. The OT dosage guidelines for labor augmentation should be individualized according to clinical response rather than generalized.
Trial registration
Clinical trial registration: ClinicalTrials.gov ID NCT04093479.
Funder
Forskningsrådet i Sydöstra Sverige
ALF-grants, Region Östergötland
The Swedish research Council
The Erasmus+ Programme of the European Union EACH EM JMD
Publisher
Public Library of Science (PLoS)