PLAC1 mRNA levels in maternal blood at induction of labor correlate negatively with induction-delivery interval.

Objective: This study was conducted to determine whether, in low risk women having labor induced using prostaglandin gel (dinoprostone gel), there is a relationship between the concentration of mRNA for the PLAC1 gene (a trophoblast-specific gene) in maternal blood and the time elapsed between the first gel administration and spontaneous delivery.

Study Design: Blood was collected from 49 selected women at 40.2-41.4 weeks' gestation. Total RNA was extracted by means of an ABI Prism 6100 nucleic acid Prep Station and quantitative real-time PCR analysis was performed by use of a PE Applied Biosystems 5700 Sequence Detection System. Sequence data were obtained from the Genebank Sequence Database. To determine the amount of cDNA, the PLAC1 locus was used.

Results: Thirty women (61.2%) had a spontaneous delivery. A caesarean section, either for fetal dystocia or fetal distress, was performed in 19 (38.8%). The crude delivery rates of the women who ended up with a spontaneous delivery were 30% at 24 h and 43% at 48 h. Women (n=19) with a blood concentration of logPLAC1 mRNA>or=2.00 displayed a median time to delivery of 23.50h, (95% CI: 13.13-33.87) while those with a logPLAC1 mRNA<2.00 (n=30) had a median time of 54 h. (95% CI: 37.86-70.14; p=0.0043, log-rank test). By means of multivariate analysis, quantitative Bishop score (from 2 to 7) at the time of the first gel administration and logPLAC1 mRNA>or=2.00 were associated with a higher rate of delivery per unit of time with an odds ratio of 1.35 (95% CI: 1.07-1.71) and 3.48 (95% CI: 1.55-7.80), respectively.

Conclusions: In induced term pregnancies, PLAC1 mRNA in maternal blood at the beginning of the treatment correlates with the time elapsed before delivery. This evidence demonstrates that the fetomaternal trafficking of nucleic acids is more consistent when the labor is about to begin.