Maternal blood and amnionic oxytocin receptor gene expression and serum oxytocin levels in preterm birth: a case control study

ABSTRACT Background The oxytocin (OXT)-oxytocin receptor ( OXTR) system provides promising candidate gene for studies of genetic contributions to prematurity. Objective Quantification and comparison of oxytocin receptor ( OXTR ) gene expression and serum OXT levels in the blood and amnion of women delivering preterm and evaluation of the correlation between OXTR gene expression in blood and amnion with serum OXT levels in them. Methods 70 pregnant women in spontaneous labor delivering vaginally preterm i.e < 37 weeks and equal number of matched controls delivering spontaneously at term (37-42 weeks) were recruited. Maternal serum OXT levels taken in active stage of labor i.e 4 cm cervical dilatation were quantified by ELISA. Gene expression studies in the maternal blood and amnion were done by using real time quantitative polymerase chain reaction (RT-qPCR). Results The mean serum OXT level in PTL was 48.56 ± 6.97 pg/ml; significantly higher than in controls (43.00 ± 3.96 pg/ml), p<0.001. OXTR gene expression both in maternal blood (2.5 times) and amnion (3.5 times) were significantly higher in PTL. A significant positive correlation was observed between serum OXT levels and OXTR gene expression in amnion (r = −0.190, p = 0.025). Conclusions The serum OXT levels and OXTR gene expression in amnion surge significantly in active phase of PTL. Thus, amnion probably links OXT-PTGs autocrine paracrine circuit to facilitate PTL. Future studies are needed to devise better OXTR receptor antagonists preferably acting on amnionic OXTRs to prevent PTL.