Background: The suggestion that garlic may lower blood pressure, inhibit platelet aggregation, and reduce oxidative stress has led to the hypothesis that it may have a role in preventing pre-eclampsia and its complications.
Objectives: To assess the effects of garlic on prevention of pre-eclampsia and its complications.
Search strategy: We searched the Cochrane Pregnancy and Childbirth Group Trials Register (February 2006), the Cochrane Central Register of Controlled Trials (The Cochrane Library 2005, Issue 2), and EMBASE (1974 to April 2005).
Selection criteria: Studies were included if they were randomised trials evaluating the effects of garlic on prevention of pre-eclampsia and its complications.
Data collection and analysis: Two review authors independently selected trials for inclusion and extracted data. Data were entered on Review Manager software for analysis, and double checked for accuracy.
Main results: One trial (100 women) of uncertain quality compared garlic with placebo. Another study was excluded as 29% of women were lost to follow up. There was no clear difference between the garlic and control groups in the risk of developing gestational hypertension (relative risk (RR) 0.50, 95% confidence interval (CI) 0.25 to 1.00) or pre-eclampsia (RR 0.78, 95% CI 0.31 to 1.93). Women allocated garlic were more likely to report odour than those allocated placebo (RR 8.50, 95% CI 2.07 to 34.88), but there were no significant differences in other reported side-effects. The only other outcomes reported were caesarean section (RR 1.35, 95% CI 0.93 to 1.95), and perinatal mortality. There were no perinatal deaths in the study.
Authors' conclusions: There is insufficient evidence to recommend increased garlic intake for preventing pre-eclampsia and its complications. Although garlic is associated with odour, other more serious side-effects have not been reported. Further large randomised trials evaluating the effects of garlic are needed before any recommendations can be made to guide clinical practice.