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.
Koopmans CM, Bijlenga D, Groen H, Vijgen SM, Aarnoudse JG, Bekedam DJ, van den Berg PP, de Boer K, Burggraaff JM, Bloemenkamp KW, Drogtrop AP, Franx A, de Groot CJ, Huisjes AJ, Kwee A, van Loon AJ, Lub A, Papatsonis DN, van der Post JA, Roumen FJ, Scheepers HC, Willekes C, Mol BW, van Pampus MG; HYPITAT study group.
Lancet. 2009 Sep 19;374(9694):979-88.

Hypertensive disorders in pregnancy are relatively common (6-8% of pregnancies) and are associated with significant morbidity and mortality. However, it is uncertain whether induction of labour after 36 weeks or expectant monitoring improves outcomes for women with gestational hypertension or mild pre-eclampsia.

In view of that, a multicentre, randomised, parallel controlled trial with 756 women from 36 to 41 weeks' gestation with gestational hypertension or mild pre-eclampsia was performed from October 2005 to March 2008 in the Netherlands comparing induction of labour to expectant monitoring. This was a 1:1 ratio, intention-to-treat trial. Inclusion and exclusion criteria were adequate. Sample size was calculated on incidence of poor maternal outcomes as reported by the National Dutch Perinatal Registry. Computer-generated, cluster randomisation was applied, however concealment and blinding could not be achieved due to the nature of the intervention. No significance difference in the two groups' baseline characteristics was noted.

The results indicate that induction of labour after 36 weeks reduces the incidence of poor maternal outcomes (including maternal mortality, morbidity, eclampsia, HELLP syndrome, pulmonary oedema, thromboembolic disease and progression to severe pre-eclampsia) by 71% (95% CI 59%- 86%, p<0.0001) in comparison to expectant management. Moreover, there was no statistically significant difference in the mode of delivery between the two groups.

This was the first trial on management of women with gestational hypertension or mild pre-eclampsia. A statistical significant reduction of poor maternal outcomes was reported that might also be clinical significant and cost-effective, as indicated by the number needed to treat of 8. Further trials are needed to confirm the above outcomes, to determine the optimum gestation age lower limit at which induction will be beneficial and to examine possible neonatal outcomes following early induction.