Up-regulation of oxytocin receptor expression at term is related to maternal body mass index.

ABSTRACT

BACKGROUND: The likelihood of cesarean is in part related to maternal body mass index (BMI). Myometrial changes may be responsible. METHODS: Myometrial biopsies were collected from the upper edge of the hysterotomy from women undergoing scheduled cesarean with term, singleton gestations. Oxytocin receptor and connexin-43 mRNA protein expression was quantified with real-time polymerase chain reaction and Western blot. RESULTS: Twenty subjects were recruited 13 repeat and 7 primary cesareans. Oxytocin receptor mRNA was associated with BMI among women undergoing primary (r = 0.75; p = 0.05) but not repeat cesarean (p > 0.05). Controlling for gestational age, this association strengthened (p = 0.004). Receptor protein expression showed a linear correlation with BMI in the primary cesarean group (p = 0.002). Connexin-43 mRNA expression was not related to BMI in women undergoing primary (r = -0.14, p = 0.76) or repeat (r = -0.01, p = 0.86) cesarean. CONCLUSIONS: Oxytocin receptor, but not connexin-43, expression is related to BMI, suggesting an alteration in oxytocin receptor expression or function related to obesity.