Drugs for treatment of very high blood pressure during pregnancy
Abstract
Background
Very high blood pressure during pregnancy poses a serious threat to women and their babies. Antihypertensive drugs lower blood pressure. Their comparative effects on other substantive outcomes, however, is uncertain.
Objectives
To compare different antihypertensive drugs for very high blood pressure during pregnancy.
Search methods
We searched the Cochrane Pregnancy and Childbirth Group Trials Register (28 February 2006) and CENTRAL (The Cochrane Library 2006, Issue 2). We updated the search of the Cochrane Pregnancy and Childbirth Group Trials Register on 13 February 2012 and added the results to the awaiting classification section.
Selection criteria
Studies were randomised trials. Participants were women with severe hypertension during pregnancy. Interventions were comparisons of one antihypertensive drug with another.
Data collection and analysis
Two review authors independently extracted data.
Main results
Twenty‐four trials (2949 women) with 12 comparisons were included. Women allocated calcium channel blockers rather than hydralazine were less likely to have persistent high blood (five trials, 263 women; 6% versus 18%; relative risk (RR) 0.33, 95% confidence interval (CI) 0.15 to 0.70). Ketanserin was associated with more persistent high blood pressure than hydralazine (four trials, 200 women; 27% versus 6%; RR 4.79, 95% CI 1.95 to 11.73), but fewer side‐effects (three trials, 120 women; RR 0.32, 95% CI 0.19 to 0.53) and a lower risk of HELLP (Haemolysis, Elevated Liver enzymes and Lowered Platelets) syndrome (one trial, 44 women, RR 0.20, 95% CI 0.05 to 0.81).
Labetalol was associated with a lower risk of hypotension (one trial 90 women; RR 0.06, 95% CI 0.00 to 0.99) and caesarean section (RR 0.43, 95% CI 0.18 to 1.02) than diazoxide. Data were insufficient for reliable conclusions about other outcomes.
The risk of persistent high blood pressure was lower for nimodipine compared to magnesium sulphate (two trials 1683 women; 47% versus 65%; RR 0.84, 95% CI 0.76 to 0.93), although nimodipine was associated with a higher risk of eclampsia (RR 2.24, 95% CI 1.06 to 4.73). Nimodipine was associated with a lower risk of respiratory difficulties (RR 0.28, 95% CI 0.08 to 0.99), fewer side‐effects (RR 0.68, 95% CI 0.54 to 0.86) and less postpartum haemorrhage (RR 0.41, 95% CI 0.18 to 0.92) than magnesium sulphate. Stillbirths and neonatal deaths were not reported.
There are insufficient data for reliable conclusions about the comparative effects of any other drugs.
Authors' conclusions
Until better evidence is available, the choice of antihypertensive should depend on the clinician's experience and familiarity with a particular drug, and on what is known about adverse effects. Exceptions are diazoxide, ketanserin, nimodipine and magnesium sulphate, which are probably best avoided.
[Note: The 37 citations in the awaiting classification section of the review may alter the conclusions of the review once assessed.]
PICOs
Plain language summary
Drugs for treatment of very high blood pressure during pregnancy
Pregnant women with very high blood pressure (hypertension) who take antihypertensive drugs can reduce their blood pressure, but the most effective antihypertensive drug is unknown.
During pregnancy a woman's blood pressure falls then climbs slowly, reaching pre‐pregnancy levels at term. Pregnant women with very high blood pressure often develop other complications such as pre‐eclampsia and premature delivery. They are also at risk of having a stroke. The review of 24 trials including 2949 women found that while antihypertensive drugs lower blood pressure, there is not enough evidence to show which drug is the most effective when taken by pregnant women with hypertension. There is some evidence that diazoxide may result in the woman's blood pressure falling too quickly, and that ketanserin may not be as effective as hydralazine. Further research into the effects of antihypertensive drugs is needed.
