Abstract:

Objective To analyse the changes of maternal plasma placental leucine aminopepticlase (P-LAP) and interleukin-6 (IL-6) levels during third trimester in spontaneous preterm labor. Methods Maternal plasma P-LAP and IL-6 levels were detected by enzyme-linked immunosorbent assay in preterm labor group（n=52）, threatened preterm labor group (n=33) and control （normal labor）group (n=137). In preterm labor group, the P-LAP and IL-6 levels of the pregnant women with subclinical chorioamnionitis (SC) (n=41）were compared with those without SC (n=11). ROC curve was employed to analyse the maternal plasma P-LAP and IL-6 levels of spontaneous preterm labor to predict the inevitable preterm labor, and the correlation of P-LAP and IL-6 was explored with Pearson analysis. Results The plasma P-LAP and IL-6 levels in preterm labor group were lower than those in threatened preterm labor group and control group（P<0.01）, while there was no significant difference between control group and threatened preterm labor group（P>0.05）. There was no significant difference in plasma P-LAP and IL-6 levels between the pregnant women with SC and those without SC (P>0.05）. It was revealed by ROC curve analysis that P-LAP≤38.12 U/L and IL-6≥3.40 pg/mL could be adopted as criteria to predict the inevitable preterm labor, and the Youden's index of the combination use of the parameters of P-LAP and IL-6 was significantly higher than that of the single use of each parameter（P<0.05）. Maternal plasma P-LAP level was correlated to IL-6 level（r=-0.311，P<0.01）. Conclusion Preterm labor can be more accurately predicted by combination detection of plasma P-LAP and IL-6. The oversecretion of IL-6 may lead to the decrease of P-LAP, which may be the key factor for spontaneous preterm labor.

Key words: placental leucine aminopepticlase, interleukin-6, preterm labor, threatened preterm labor