Pregnancy induced hypertension and preeclampsia are common complications of pregnancy [1
]. In many cases, the clinical presentation is mild, consisting only of mild hypertension and/or mild proteinuria at term. In other cases however, severe maternal and fetal complications such as eclampsia, abruptio placentae, preterm delivery, the Hemolysis Elevated Liver enzymes and Low Platelet count syndrome (HELLP), fetal growth restriction or even intra-uterine fetal death may occur. Hypertensive disorders in pregnancy make a major contribution to maternal and neonatal mortality. In the Netherlands, hypertensive disorders in pregnancy are the largest single cause of maternal mortality [2
Approximately 10% to 15% of all pregnancies are complicated by hypertensive disorders. The vast majority of these cases occur after 32 weeks. The only causal treatment of the disease is delivery. In case of preterm pregnancies (28–34 weeks gestational age) complicated by preeclampsia expectant monitoring is advocated to increase the chance of fetal maturity, as long as the risks for the mother remain acceptable [3
]. Expectant management reduces neonatal complications and duration of neonatal stay in the intensive care unit in preterm pregnancies and is not associated with an increase in maternal complications [4
In case of pregnancy induced hypertension or preeclampsia at term, the situation is different from preterm disease. In women with mild preeclampsia complications such as abruptio placenta and small for gestational age are similar to normotensive pregnancies. It is unclear whether in this situation expectant management is beneficial for the mother and her baby, since evidence is lacking. Despite this lack of evidence delivery is often recommended because of the unpredictability of the disease [4
]. Recent observational studies indicate that the onset of mild gestational hypertension or mild preeclampsia at or near term is associated with minimal to low maternal and neonatal morbidity [6
]. Despite the lack of evidence that would justify intervention, many obstetricians induce labour in women at term with pregnancy-induced hypertension or preeclampsia. Such a policy may increase the risk of assisted vaginal delivery and caesarean section, thus generating additional morbidity and costs [9
]. On the other hand, expectant management might lead to severe pregnancy complications like eclampsia, severe hypertension, HELLP syndrome, organ failure or an adverse neonatal outcome.
Data from the Dutch National Obstetric Registration from 2002 showed that the yearly number of patients with hypertension (blood pressure [BP] diastolic above 90 mmHg) without proteinuria at term is 17.000. Moreover, there are 2.000 women with preeclampsia at term. The lack of consensus is demonstrated by the fact that in 9.000 women with pregnancy induced hypertension or preeclampsia labour was induced, whereas labour started spontaneously in 10.000 women. Moreover, national data indicate no impact of induction of labour on neonatal outcome. In 2002 and 2003, the rate of babies born with a 5-minute Apgar score below 7 was 1.3% among women that delivered after a spontaneous onset of labour, versus 1.6% among women in whom labour was induced (OR 1.2 95% CI 1.0 to 1.5). After adjustment for potential confounders such as fetal weight, proteinuria and diastolic blood pressure, this difference became statically insignificant despite the analysis of over 35.000 patients (OR 1.1 95% CI 0.98 to 1.2). Since this equivalence is also expected from the pathophysiological background of the problem as well as from the medical literature, we anticipate no differences in neonatal outcome between both strategies.
Data from the Dutch National Obstetric Registration from Januari 2000 until Januari 2005 show that 38.170 nullipara had a singleton pregnancy in cephalic presentation complicated with pregnancy induced hypertension or preeclampsia. In 18.012 women labour started spontaneously, whereas in 18.810 labour was induced. The non-elective caesarean section rate among women in whom labour started spontaneously was 14% and among women in whom labour was induced this rate was 22% (OR 1,7 95% CI 1,6 to 1,8). The vaginal instrumental delivery rates among these groups were 28% and 24% (OR 0,88 95% CI 0,84 to 0,93).
At present, there is no evidence on the effectiveness and efficiency of induction of labour in women with pregnancy induced hypertension or mild preeclampsia (nearly) at term as compared with expectant management with close monitoring. In post term women and women with ruptured membranes at term, randomised trials have indicated that induction of labour does not increase the instrumental delivery rate [12
]. However, the fact that the women were post term, might implicate that myometrial gapjunctions facilitating effective contractions were present [12
]. These data can not be extrapolated to women who are (nearly) at term with pregnancy induced hypertension or preeclampsia.
In view of this clinical dilemma, we propose a randomised clinical trial in which a policy of induction of labour, if necessary preceded by artificial cervical ripening, is compared with a policy of careful expectant monitoring in women with pregnancy induced hypertension or mild preeclampsia (nearly) at term. At present – to our knowledge – no clinical study has been published or undertaken to investigate this issue.