Mass spectrometry-based quantitation of cervicovaginal progesterone and steroids in women at high risk of preterm birth

Abstract

Placental production of steroids, like progesterone, drives increasing circulating concentrations during pregnancy. It is postulated that reduced cervicovaginal progesterone contributes to cervical shortening and increased preterm birth (PTB) risk. Although vaginal progesterone is recommended for PTB prevention, its effectiveness remains uncertain. While serum and urinary progesterone are routinely measured in pregnancy, little is known about cervicovaginal fluid (CVF) progesterone concentrations. To address this, we adapted existing mass spectrometry-based assays to quantify 13 steroid hormones in CVF collected between 12–24 weeks gestation from uncomplicated term pregnancies (n = 14) and those with adverse outcomes (n = 11). Only progesterone, androstenedione, and cortisol were detected above detection limits. In uncomplicated term pregnancies, mean concentrations of these steroids were 6.61 ± 8.13, 4.16 ± 2.98 and 0.34 ± 0.21 ng/g of CVF, respectively. Cervicovaginal progesterone was weakly, positively associated with gestational age (r2= 0.15, p-value= 0.02) which was also observed in paired samples collected at 12 and 22 weeks (n = 5, paired Wilcoxon, p-value = 0.03). No differences in CVF steroid levels were observed between women who subsequently delivered preterm (n = 9) or at term (n = 15). Our study provides a robust method for quantifying CVF steroids and suggests that second-trimester PTB risk is not associated with cervicovaginal progesterone concentrations.