Abstract

The normal physiological end point of pregnancy is signalled by the onset of myometrial contractions. However, the biochemical processes may have already occurred at or before term via a series of changes in the expression of pro-labour genes. Prostaglandin H synthase (PGHS-2), CXCL-8 and oxytocin receptor (OTR) have been recognised as markers of labour. Our aim was to determine the changes in these prolabour genes during labour.

Lower segment myometrium samples were taken from pregnant women undergoing caesarean section either before labour (TNL, n = 19) or after the onset of labour. Term labour was further classified into 2 groups, early labour (EAL, cervical dilatation ≤ 2 cm, n = 19) and established labour (ESL ≥ 3 cm, n = 24). Samples were rapidly frozen at –70°C, RNA extracted and converted to cDNA.

Real-time PCR was used to measure copy numbers of GAPDH, PGHS-2, CXCL-8 and OTR.

Significant increases were seen in PGHS-2 (0.77 ± 0.14) and OTR (15.19 ± 2038) expression in EAL, when compared with TNL samples (0.26 ± 0.06 and 8.6 ± 1.61 respectively; p < 0.05 in each case). However CXCL-8 was significantly increased only in ESL (TNL, 0.38 ± 0.09; ESL 56.16 ± 46.01, p < 0.05. These data show that there are differences in the gene expression at different stages of term labour. PGHS-2 and OTR are increased in early labour whereas CXCL-8 is increased only in established labour.