Introduction:
The aim of the present study was to evaluate cervical mucus secretory leukocyte protease inhibitor (SLPI) levels for the prediction of delivery time in uncomplicated term nulliparous pregnancies with an unfavorable cervix.

Material and methods:
In this prospective study, a total of 88 nulliparous singleton pregnant women with a gestational age between 370/7and 376/7 weeks were included. Bishop Score was determined and unfavorable cervix was defined as a Bishop Score <5. Cervical mucus SLPI levels were collected from pregnant women with an unfavorable cervix between 370/7and 376/7gestational weeks. Patients were divided into two groups according to gestational age at delivery after cervical mucus SLPI sampling: delivery within 2 weeks group (n: 48) and delivery after 2 weeks group (n: 40).

Results:
Maternal demographic characteristics, mean Bishop Score, transvaginally measured cervical length, and cervical dilatation at cervical mucus SLPI sampling were similar between the two groups. The mean cervical mucus SLPI level was 52.4±52.6 ng/mL in the delivery after 2 weeks group and 253.2±220.0 ng/mL in the delivery within 2 weeks group and statistically different. The optimal SLPI cutoff value was 32 ng/mL for predict labor induction requirement due to absence of spontaneous labor before 410/7 (sensitivity, 0.65; specificity, 0.93; positive predictive value, 0.52; negative predictive value, 0.95).

Conclusions:
Our results suggest that measuring the SLPI levels in the cervical mucus can be a useful biomarker for predicting spontaneous delivery time in uncomplicated term nulliparous pregnancies with an unfavorable cervix.