Since 1997, [
7] a test using cell free fetal DNA (cffDNA) in maternal blood has been developed to identify the genotype of the fetus and can be used to predict the fetal RhD blood group. This was initially used in women who had already been sensitised and so were at risk of HDFN [
8,
9], however, from 2008 modifications were made to allow a scaled-up high throughput approach [
10]. Standardisation of the test has been the focus of international research, and it has been shown to be very accurate but the small possibility of false negative results remains. If the test gave a false negative result and routine cord blood phenotype testing at birth subsequently identified the fetus as RhD positive then postnatal Anti-D Ig would still be administered at that time, but potentially sensitisation could occur in these women affecting subsequent pregnancies. The risks of this happening have been estimated to be 1:86,000 [
2]. In the UK, non-invasive (or invasive) fetal blood group genotyping is currently only performed when women’s samples are referred to the NHS Blood and Transplant (NHSBT) or Scottish National Blood Transfusion Service (SNBTS) [
11] for testing to determine the risk to the fetus when a mother is known to have immune antibodies against the relevant blood group antigen. A multicentre “research for patient benefit” NIHR project has finished recruiting and is awaiting publication. In addition a service implementation pilot that offers a fetal genotyping test to all RhD negative women is now underway in Bristol and Weston and results are expected in late 2014 [
12]. Only the Netherlands and Denmark currently offer this test to all RhD negative women in order to identify those carrying a fetus that is RhD negative and to reduce the unnecessary administration of Anti-D Ig [
13,
14]. In Denmark, the decision was made concurrently with the implementation of RAADP and it was recognised that the accuracy of fetal
RHD genotyping was similar to that of the cord blood RhD phenotyping used for the administration of postnatal Anti-D Ig. In the Netherlands, RAADP had already been established when fetal
RHD genotyping began to be offered to all RhD negative women in 2011.