MON-003 Uterine Contractility in Pregnancies Complicated by Obesity: The Effects of Adipokines on the in Vitro Functional Contractility of Isolated Uterine Samples

Abstract

Objectives: The onset of parturition in pregnant women with obesity is frequently delayed. Without induction, these women are nearly twice as likely as normal-weight to have prolonged pregnancy (≥41 weeks gestation) which is concerning because of associated two-fold increased risk of third-trimester stillbirth. Data from vascular studies have shown that different adipokines have different effects on smooth muscle contractility; either as relaxants or constrictors. However, only few studies have investigated their role in uterine contractility, a relationship that we sought to investigate. Materials and Methods: Total of 22 pregnant women scheduled for term cesarean delivery (CD) were recruited. Strips from the first two participants were used to identify dose response effects for each adipokine, and 20 participants’ data were included in the final analysis. Study groups consisted of normal-weight (N=10) and women with obesity (N=10). Myometrial strips were obtained from the hysterotomy incision at the time of the CD. Muscle strips were mounted within experimental recording baths. Both spontaneous and oxytocin induced contractions were recorded by a custom-build data acquisition software. Adipokines of interest included adiponectin, TNFα, resistin, and omentin. Adipokines were added to the muscle baths after muscle equilibration was achieved. Contractions outcomes of interest included forces, durations, and frequencies. Data comparisons were conducted using Wilcoxon Rank-Sum tests; medians and ranges are presented. Results: Forces of contractions in normal-weight participants were double those studied from participants with obesity (13.9 [9.3-34.3] vs. 8.9 [4.8-23.6], p=0.05). There were no statistically significant differences between contractility outcomes of interest after adding adiponectin, TNFα, and resistin to the muscle baths within and between the study groups. In participants with obesity, compared to baseline, omentin significantly reduced the force of spontaneous induced contractions (p=0.002) and prolonged the period between contractions (p=0.01). Importantly, that effect was not seen in normal-weight participants or in oxytocin induced contractions. Omentin also significantly reduced the forces of spontaneous induced contractions (2.9 [2.2-4.6] vs. 14.4 [4.8-33.6]; p=0.01) and prolonged the period (790.6 [753.0-832.0] vs. 611.4 [128.3-702.7]; p=0.04) in participants with obesity compared to normal-weight participants. Differences were no longer observed after adding oxytocin. Conclusion: In vitro, uterine contractions were reduced in muscle samples prepared from pregnant women with obesity compared to normal-weight counterparts. Omentin may have a role in reduced uterine contractility in pregnant women with obesity and that effect may be corrected by oxytocin administration.