[Comparison of the efficacy of different methods for the prevention of anti-D allo-immunization during pregnancy: targeted strategy limited to risk situations or associated with systematic prevention in the 3rd trimester]

Abstract

Background: In France, anti-Rh prophylaxis is currently based on systematic postnatal prevention which has validated efficacy (relative risk=0.04 versus placebo), associated with targeted antenatal prevention in the event of situations raising a risk of fetomaternal hemorrhage. In most industrialized countries, a systematic prevention policy is applied with immunoglobulin injections for the above cited situations and during the third trimester to cover the risk of spontaneous occult fetomaternal hemorrhage occurring at the end of pregnancy.

Objective: Compare the efficacy of two strategies for antenatal prevention.

Material and methods: Review of the literature of published comparative studies. Eleven studies were retained (two randomized trials, seven comparative studies, one before-after study, one population-based study) including more than 30,000 treated patients.

Results: Globally, immunization rate was to the order of 1.5% (1.2-1.9%) for targeted prevention limited to situations at risk and to the order of 0.2% (0-0.9%), all parities included, for systematic antenatal prevention. Comparative analyses have reported significant odds ratios of 0.20 and 0.37 in all subgroups.

Conclusion: Despite the heterogeneous nature of the published studies, available data are in favor of systematic prevention: either with a 300g dose at 28GW or 100g at 28GW and 34GW complementary to the postnatal prevention. Few data are available on the real perinatal benefit of systematic prevention.