ArticlesInduction of labour versus expectant monitoring for gestational hypertension or mild pre-eclampsia after 36 weeks' gestation (HYPITAT): a multicentre, open-label randomised controlled trial
Introduction
About 6–8% of pregnancies are complicated by hypertensive disorders.1, 2 Such disorders in pregnancy make a substantial contribution to maternal and neonatal morbidity and mortality worldwide.3 In the Netherlands these disorders are the primary cause of maternal mortality.4, 5 Most hypertensive disorders present after 36 weeks' gestation. For the management of women with gestational hypertension or mild pre-eclampsia at term, evidence for selection of induction of labour versus expectant monitoring is scarce. Induction of labour is thought to prevent severe maternal and neonatal complications such as eclampsia, HELLP syndrome (haemolysis, elevated liver enzymes, and low platelet count), placental abruption, maternal death, and asphyxia. Conversely, induction might increase the risk of instrumental vaginal delivery and caesarean section, and thereby generate additional morbidity and costs.6, 7, 8
To our knowledge, no randomised clinical trial on this subject has yet been published. Strong practice variation exists in the Netherlands for treatment of women with gestational hypertension or mild pre-eclampsia beyond 36 weeks' gestation. Therefore we aimed to assess whether induction of labour in such women reduces poor maternal outcome compared with expectant monitoring.
Section snippets
Patients
We did a multicentre, parallel, open-label randomised controlled trial in the Netherlands, in which six academic and 32 non-academic hospitals participated. We recruited women with a singleton pregnancy and a fetus in cephalic presentation at a gestational age of between 36 (0 days) and 41 weeks (0 days), and who had gestational hypertension or mild pre-eclampsia. Gestational hypertension was defined as diastolic blood pressure of 95 mm Hg or higher measured on two occasions at least 6 h apart.
Procedures
Patients allocated to induction of labour were induced within 24 h of randomisation. If the patient had a Bishop score13 of more than 6 at vaginal examination, labour was induced with amniotomy and, if needed, augmentation with oxytocin. If the Bishop score was 6 or lower, cervical ripening was stimulated with intracervical or intravaginal prostaglandins or a balloon catheter. Use of oxytocin or prostaglandins depended on local protocols, which were based on national guidelines of the Dutch
Results
Between October, 2005, and March, 2008, we identified 1153 eligible women, of whom 756 gave informed consent for randomisation. We randomly assigned 377 patients to induction of labour and 379 to expectant monitoring (figure 1). Of the 397 patients who refused randomisation, most (82%) had expectant monitoring and only 18% had induction of labour. Baseline characteristics of all eligible women (table 1) showed that women in the randomised group, compared with those in the non-randomised group,
Discussion
The results of this study show that induction of labour was associated with a lower composite risk of poor maternal outcome, which was mainly ascribed to progression to severe disease, than was expectant monitoring. Overall, 13 per 100 fewer women allocated to induction of labour had a poor maternal outcome, corresponding with a number needed to treat of eight. Surprisingly, fewer caesarean sections were needed in the induction group than the expectant monitoring group. Adverse neonatal
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