Salivary progesterone and estriol among pregnant women treated with 17-alpha-hydroxyprogesterone caproate or placebo

Abstract

Objective: The objectives of the study was to determine whether salivary progesterone (P) or estriol (E3) concentration at 16-20 weeks' gestation predicts preterm birth or the response to 17alpha-hydroxyprogesterone caproate (17OHPC) and whether 17OHPC treatment affected the trajectory of salivary P and E3 as pregnancy progressed.

Study design: This was a secondary analysis of a clinical trial of 17OHPC to prevent preterm birth. Baseline saliva was assayed for P and E3. Weekly salivary samples were obtained from 40 women who received 17OHPC and 40 who received placebo in a multicenter randomized trial of 17OHPC to prevent recurrent preterm delivery.

Results: Both low and high baseline saliva P and E3 were associated with a slightly increased risk of preterm birth. However, 17OHPC prevented preterm birth comparably, regardless of baseline salivary hormone concentrations. 17OHPC did not alter the trajectory of salivary P over pregnancy, but it significantly blunted the rise in salivary E3 as well as the rise in the E3/P ratio.

Conclusion: 17OHPC flattened the trajectory of E3 in the second half of pregnancy, suggesting that the drug influences the fetoplacental unit.

FIGURE 1. Preterm birth by treatment (17P/placebo) and baseline salivary progesterone and estriol percentiles

Klebanoff. Salivary progesterone and estriol among pregnant women treated with 17-α-hydroxyprogesterone caproate or placebo. Am J Obstet Gynecol 2008.

FIGURE 2. Weekly values of salivary progesterone, estriol, and the progesterone/estriol ratio according to treatment group

Weekly values of salivary progesterone (A), estriol (B), and the progesterone/estriol ratio (C) according to treatment group. P value for difference in slope between drug- and placebo-treated women = .38 for progesterone, .013 for estriol, and .003 for progesterone/estriol ratio. Klebanoff. Salivary progesterone and estriol among pregnant women treated with 17-α-hydroxyprogesterone caproate or placebo. Am J Obstet Gynecol 2008.