Hypertension and patterns of induced labor at term

To study patterns of induced labor at term in hypertensive women.

We performed a retrospective cohort study using the Consortium on Safe Labor database; a multicenter study of labor and delivery practices from electronic medical records in 19 hospitals. 55,572 women were studied: 28,254 nulliparas and 27,318 multiparas, undergoing induction of labor at term without a prior cesarean with a singleton vertex live born fetus. Four hypertensive groups were defined: chronic hypertension (n=1164), gestational hypertension (n=1861), preeclampsia (n=1513) and superimposed preeclampsia (n=655), compared to controls (no hypertension, n=50,379). Labor characteristics and patterns were compared among the groups, stratified by parity.

Interval-censored regression analysis estimated median and 95th% duration of labor, stratified by centimeter-by-centimeter dilation. Repeated-measures analysis established mean labor curves.

Time to progress from 4 to 10 cm was 7.5, 6.4, 4.9 and 4.6h in nulliparous women with superimposed preeclampsia, chronic hypertension, preeclampsia and gestational hypertension respectively, which differed from controls (4.9h; p<0.05 for chronic hypertension and superimposed preeclampsia). Multiparous women required 3.8, 3.9, 3.2 and 3.3h, respectively, compared to controls (3.2h, p<0.05 except preeclampsia p=0.1) to progress from 4 to 10cm. Second stage of labor without epidural was longer for all nulliparous groups compared to controls except for women with chronic hypertension, but second stage did not differ in multiparas.

Regardless of parity, women with chronic disease, chronic hypertension and superimposed preeclampsia, labor longer whereas those with relatively acute disease, gestational hypertension and preeclampsia, progress more rapidly.