A single-dose regimen of routine antenatal Rhesus immunoglobulin (RhIG) prophylaxis has been associated with higher compliance rates than a two-dose regimen, when used to decrease the incidence of hemolytic disease of the fetus and newborn (HDFN) and RhD alloimmunization, according to findings from a systematic review and meta-analysis published recently in the Journal of Blood Disorders & Transfusion.
The introduction of RhIG in the late 1960s has dramatically reduced the occurrence of anti-D–facilitated HDFN and RhD alloimmunization. RhIG is generated by purification of human polyclonal anti-D immunoglobulin G (IgG) that has been derived from pooled plasma of hyperimmunized male donors. Guidelines and approaches for administering RhIG prophylaxis vary in many countries, particularly developed nations.
It is well recognized that antenatal prophylaxis comprises the administration of RhIG to all nonimmunized RhD-negative pregnant women at risk for RhD alloimmunization. The researchers of the current systematic literature review and meta-analysis sought to explore the compliance with and effectiveness of routine antenatal prophylaxis using different strategies by calculating the detectable anti-D levels at delivery, rates of RhD alloimmunization, and compliance with the routine antenatal prophylactic regimen.
The literature search was performed using all relevant publications through July 30, 2023. Eligible studies were evaluated for their reporting quality via utilization of the recommendations described in the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines. A total of 19 studies were included in the literature review, with 17 of them included in the meta-analysis.
Read more about HDFN symptoms and risks
Among the 19 eligible studies, there were nine retrospective studies, five clinical trials, four prospective studies and one study with an unspecified design. The studies were carried out in eight countries (Australia, Canada, Denmark, Israel, Norway, Sweden, United Kingdom and the United States) between 1975 and 2019. In one of the studies, information on the study period was not available.
Results of the study showed that a higher proportion of women exhibited detectable anti-D at delivery following a two-dose regimen than following a one-dose regimen. Moreover, the rate of RhD alloimmunization was higher among women treated with the two-dose regimen compared with the one-dose regimen.
The use of targeted antenatal RhIG was associated with the highest compliance rates (90.01%; estimate, 0.903; 95% CI, 0.880-0.924; P <.001). The single-dose regimen was associated with statistically significantly higher compliance rates than the two-dose regimen (88.73% vs 61.49%, respectively; P =.004).
“Overall, both one-dose and two-dose regimens were equally effective[,] although slight differences in detectable anti-D and RhD [alloimmunization] were observed,” the authors reported. “The targeted regimen [that] uses a single dose of RhIG is considered the best strategy for routine antenatal prophylaxis with the highest compliance.”
