Introduction Antihypertensive drugs lower blood pressure by direct vascular effects or central vasodilatory mechanisms. Methyldopa is a commonly used in hypertensive disorders in pregnancy. Although methyldopa is effective in controlling maternal blood pressure, its effects on fetal growth and wellbeing is unknown. The aim of this study was to ascertain the effect of methyldopa on uterine artery and fetal dopplers in women with hypertensive disorders in pregnancy.

Methods MEDLINE (1966 – March 2012), EMBASE (1974 - March 2012) and The Cochrane library (inception–March 2012), utilising combinations of the terms methyldopa, hypertens*, pre-eclamp*, preeclamp*, pre eclamp*, pregnan*, uterine, uteroplacental, umbilical, middle cerebral artery and doppler. Between-study heterogeneity was assessed using the I2 statistic.

Results The search yielded 429 citations. Full manuscripts were retrieved for 32 and 6 were included in the review and meta-analysis. Six studies (n = 188) have reported the effect of methyldopa on uterine artery doppler pulsatility index (PI). The standardised mean difference (SMD) was –0.22 (95% CI: –0.43 to –0.02). Five studies (n = 110) were included that evaluated the effect of methyldopa on umbilical artery Doppler PI. The SMD was –0.05 (95% CI: –0.32 to 0.21). Four studies (n = 82) reported the effect of methyldopa on middle cerebral artery PI. The SMD was –0.34 (95% CI: –0.65 to 0.03).

Conclusion In pregnancies complicated by hypertension, methyldopa seems to have a small favourable effect on uterine artery dopplers. These results provide reassurance that the maternal hypotensive effect of methyldopa is unlikely to have a clinically significant adverse effect on the pregnancy.