Induction for Pregnancy-Induced Hypertension and Preeclampsia After 36 Weeks Gestation

In a recent article published on line by the Lancet, there is now evidence to support induction of labor after the 36th week of pregnancy if a woman develops pregnancy-induced hypertension (PIH) or mild preeclampsia.

Study design: This multi-centered, parallel, open label, randomized study (HYPITAT) was conducted in the Netherlands. Koopman, et al recruited 756 women who presented with PIH or mild preeclampsia between the 36th and 41st weeks of pregnancy. 379 patients were expectantly monitored and 377 underwent labor induction. Another 397 women were approached to join the study and declined, but allowed their medical information to be utilized for the purposes of the study.

Question: Is it better to intervene to avoid serious complications? Which group fairs better of those women who are diagnosed after 36 weeks gestation with new-onset high blood pressure or mild pre-eclampsia: Those whose labor is induced or those who are observed?

"Serious complications" included eclampsia (seizures), HELLP syndrome, pulmonary edema, thromboembolic disease, placental abruption, severe hypertension, proteinuria or postpartum hemorrhage.

Findings: 31% of women whose labor was induced developed severe complications while 44% of those not induced developed severe complications. The findings were statistically significant.

(Relative risk 0.71, 95% CI 0.59-0.86, p<0.0001)

Implication: When a woman develops hypertension or mild preeclampsia after 36 weeks' gestation, labor induction will decrease her risk of developing severe complications by 30%.

Comment: In general, we are trying to limit labor inductions in the United States. ACOG has recently issued a Revision of Labor Induction Guidelines. However, when a woman develops hypertension or mild preeclampsia after the 36th week of pregnancy, it appears safer to induce her labor rather than await more serious complications to evolve.

Reference:
Koopmans CM, et al. Induction of labour versus expectant monitoring for gestational hypertension or mild pre-eclampsia after 36 weeks' gestation (HYPITAT): a multicentre, open-label randomised controlled trial. Lancet, 2009;374(9694):979-88