OBJECTIVE:

To evaluate if vaginal pH has any effect on the efficacy of controlled-release PGE2 vaginal insert for cervical ripening/labor induction in post-term patients.

METHODS:

Sixty-three post-term women with unfavorable cervix (Bishop’s score, ≤ 6) undergoing labor induction were enrolled in this prospective, double-blinded trial. All patients received sustained-release dinoprostone vaginal insert for cervical ripening/labor induction during 12 hrs, repeated dosing one time 24 hrs later.

RESULTS:

Women with a low vaginal pH (≤4.5, n = 38) and women with a high vaginal pH (>4.5, n = 25) were similar in maternal age, parity, body mass index, gestational age, or initial Bishop score. Bishop score change over the initial 12 hrs significantly (P < 0.05) differed between the low vaginal pH (3.9 ± 3.3) and the high vaginal pH group (5.5 ± 3.4). Time to active labor (14.7 ± 17.3 hrs vs 13.1 ± 9.8 hrs), complete dilation (19.6 ± 20.1 hrs vs 17.1 ± 11.8 hrs), and delivery (20.0 ± 21.4 hrs vs 17.6 ± 12.0 hrs) were comparable between the low and high vaginal pH groups, respectively. Linear regression analysis revealed no significant association between vaginal pH and Bishop score change over 12 hr, time to active labor, time to complete dilation, or time to delivery.

CONCLUSIONS:

Vaginal pH has significant effect on cervical ripening but has no effect on delivery outcomes in post-term patients with unfavorable cervices, who undergo cervical priming/labor induction using sustained-release dinoprostone vaginal insert.

Keywords: Dinoprostone vaginal insert, vaginal pH, cervical ripening, labor induction