Study designs of evaluations included in the review
Randomised controlled trials (RCTs) were eligible for assessing maternal and perinatal outcomes from antihypertensive treatment, and for assessing the benefits of aspirin.
Case reports, case-control, cohorts, surveillance studies, RCTs and systematic reviews were eligible for assessing the harmful effect of antihypertensive treatment.
Case series, cohort studies and RCTs were eligible for assessing foetal monitoring techniques and strategies.
Specific interventions included in the review
Pharmacologic antihypertensive agents, non-pharmacologic interventions, aspirin and foetal monitoring techniques.
The pharmacologic agents used in the identified trials included diuretics, beta-blockers and calcium-channel blockers (bendrofluazide, hydralazine, hydrochlorothiazide, metroprolol, atenolol, labetalol, isradipine sustained-release, pindolol, ketanserin, methyldopa and nifedipine).
No trials of non-pharmacologic interventions or foetal monitoring techniques met the review criteria.
Participants included in the review
Pregnant females with mild-to-moderate chronic hypertension or with chronic hypertension were eligible. Mild-to-moderate chronic hypertension was defined as a blood-pressure (BP) of less than 170/110 mmHg, diagnosed either before pregnancy or before 20 weeks' gestation. Chronic hypertension was defined as known hypertension before pregnancy and/or a BP of greater than 140/90 mmHg before 20 weeks.
The participants in the trials of pharmacologic antihypertensives were a mixed group of high- and low-risk chronic hypertensive women with an initial BP reported from 6 to 37 weeks' gestation.
For trials assessing the harmful effects of antihypertensive treatment, the criteria for selection were pregnant or non-gravid participants with exposure to an antihypertensive agent.
For studies of aspirin, the participants in the trials had to be pregnant and have mild-to-moderate chronic hypertension.
For the assessment of foetal monitoring techniques and strategies, the participants in the trials had to be pregnant and have chronic hypertension.
Outcomes assessed in the review
The outcomes assessed were maternal and/or foetal morbidity (pre-eclampsia) or mortality. The harmful effects of treatment (teratogenic, foetal or maternal) were also assessed.
How were decisions on the relevance of primary studies made?
Two reviewers screened the titles and abstracts in accordance with the preliminary inclusion criteria; searches on harmful effects were screened by only one person. At least two independent reviewers screened the full text of the initially included articles to determine the final selection.