A Cochrane review [Abstract] 1 included 6 studies with a total of over 10 000 women. The effects of giving anti-D to Rhesus negative women, with no anti-D antibodies, who had given birth to a Rhesus positive infant, were examined. Postpartum anti-D prophylaxis compared with no treatment or placebo lowered the incidence of RhD alloimmunisation 6 months after birth (RR 0.04, 95% CI 0.02 to 0.06), and in a subsequent pregnancy (RR 0.12, 95% CI 0.07 to 0.23). These benefits were seen regardless of the ABO status of the mother and baby, when anti-D was given within 72 hours of birth. Higher doses (up to 200 micrograms) were more effective than lower doses (up to 50 micrograms) in preventing RhD alloimmunisation in a subsequent pregnancy.
Comment: The quality of evidence is downgraded by study quality (unclear allocation concealment) but upgraded by large magnitude of effect.
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