Targeted antenatal anti‐D prophylaxis program for RhD‐negative pregnant women – outcome of the first two years of a national program in Finland

Introduction The aim of this study was to assess the accuracy of the non-invasive fetal RHD test at 24-26 weeks of gestation as part of the national antenatal screening programme to target routine antenatal anti-D prophylaxis (RAADP) at 28-30 weeks at women carrying an RhD-positive fetus Material and methods A prospective cohort study involving all maternity care centres and delivery hospitals in Finland between February 2014 and January 2016. Fetal RHD genotyping using cell-free fetal DNA in maternal plasma was performed with real-time polymerase chain reaction in a centralised setting. The results were systematically compared with the serological newborn RhD typing. The main outcome measure was the accuracy of the fetal RHD assay; the secondary variable was compliance with the newly introduced RAADP programme Results Fetal RHD was screened from 10 814 women. For the detection of fetal RHD, sensitivity was 99.99% (95% CI: 99.92-99.99) and specificity 99.81% (95% CI: 99.60-99.92). One false negative and seven false positive results were reported by the delivery hospitals during two years. The negative predictive value of the test was 99.97% (95% CI: 99.81-99.99). At the end of the study period, over 98% of the RhD-negative women participated in the new screening program Conclusions The targeted RAAPD program was implemented effectively in the national maternity care programme in Finland. An accurate fetal RHD screening test allows discontinuation of newborn testing without risking the postnatal prophylaxis programme. In the future, the main area to investigate will be the clinical effect of RAADP on subsequent pregnancies. This article is protected by copyright. All rights reserved.