Immunisation of Rhesus negative women with anti-D after the birth of a Rhesus positive infant reduces the chances of developing Rhesus antibodies.
Mothers and babies may have incompatible blood characteristics (such as Rhesus positive babies and Rhesus negative mothers). After the birth of a Rhesus positive infant, Rhesus negative women are given an injection of anti-D, which aims to prevent the women forming antibodies that would attack the red cells of a Rhesus positive baby in a future pregnancy. Such antibodies may make the baby anaemic and if severe enough can cause the baby to die. This review of six trials, involving over 10,000 women, found that anti-D given to Rhesus negative women within 72 hours of giving birth to a Rhesus positive infant decreased the likelihood of the women developing Rhesus antibodies within six months of the birth and in their next pregnancy.
Anti-D, given within 72 hours after childbirth, reduces the risk of RhD alloimmunisation in Rhesus negative women who have given birth to a Rhesus positive infant. However the evidence on the optimal dose is limited.
The development of Rhesus immunisation and its prophylactic use since the 1970s has meant that severe Rhesus D (RhD) alloimmunisation is now rarely seen.
The objective of this systematic review was to assess the effects of giving anti-D to Rhesus negative women, with no anti-D antibodies, who had given birth to a Rhesus positive infant.
We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (March 2010) and reference lists of relevant articles.
Randomised trials in Rhesus negative women without antibodies who were given anti-D immunoglobulin postpartum compared with no treatment or placebo.
Assessments of inclusion criteria, trial quality and data extraction were done by each author independently. Initial analyses included all trials. Other analyses assessed the effect of trial quality, ABO compatibility and dose.
Six eligible trials compared postpartum anti-D prophylaxis with no treatment or placebo. The trials involved over 10,000 women, but trial quality varied. Anti-D lowered the incidence of RhD alloimmunisation six months after birth (risk ratio (RR) 0.04, 95% confidence interval (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.