Background: Progesterone withdrawal in the initiation of labor is well established in sheep. Salivary progesterone is the biologically active form of progesterone and hence a correlation is hypothesized.

Objectives: 1) To find out the role of salivary progesterone in prediction of preterm birth in asymptomatic high risk women 2)To compare it with transvaginal cervical length.

Materials and methods: A total of 90 antenatal women satisfying the inclusion criteria were enrolled. Various demographic parameters, salivary progesterone and transvaginal cervical length were studied.

Results: Salivary progesterone estimation at 24–28 weeks and then at 29–32 weeks in asymptomatic high risk antenatal mothers is a valuable predictor of preterm labor. Its sensitivity and specificity is comparable with the transvaginal cervical length.

Conclusion:

            Salivary progesterone is a better predictor of preterm labor when compared to transvaginal cervical length, as it has better sensitivity and specificity. It is a non–invasive method and sample collection is easier.