A New Era in Prenatal Care: Fetal Blood Group Genotyping Launches in Ontario
By Prenatal Screening Ontario
May 05, 2025
A major step forward in personalized prenatal care is coming in fall 2025. Prenatal Screening Ontario (PSO) is pleased to announce that health-care providers across Ontario will soon be able to offer a new, highly accurate blood test designed to identify the RhD blood group of a fetus early in pregnancy. Additionally, alloimmunized fetal blood group genotyping will be available for select red blood cell antibodies to help guide care in pregnancies already affected by alloimmunization. This advancement has the potential to significantly change how pregnancies are managed in RhD-negative individuals and those with anti-D, C, c, E, or anti-K (Kell) antibodies.
For decades, the standard approach has been to recommend RhD immune globulin (RhIG) to all RhD negative pregnant individuals prophylactically, regardless of the fetus’ RhD blood group. However, up to 40% of these pregnancies involve a fetus who is also RhD negative and therefore not at risk – resulting in potentially unnecessary treatment. This innovative test opens the door to a more person-centered approach to RhIG administration, moving beyond the broad-brush methods of the past.
“This test allows us to identify which pregnancies are truly at risk,” says Dr. Barb deVrijer, a Maternal-Fetal Medicine specialist and advisor to the initiative. “We can now offer RhIG only when needed, reducing unnecessary interventions and aligning care with current best evidence.”
Two New Tools for Targeted Prenatal Care (Launching Fall 2025)
- Fetal RHD Screening – Offered to RhD negative pregnant individuals to determine if their fetus is RhD positive. If the fetus is RhD negative, RhIG can be avoided, reducing unnecessary exposure to a blood product.
- Alloimmunized Fetal Blood Group Genotyping (Allo-FBGG) – Available for pregnancies affected by specific red blood cell antibodies (anti-D, anti-C, anti-c, anti-E and anti-K (Kell)). This test helps determine whether the fetus carries the red blood cell antigen that corresponds to the pregnant person’s antibody. If the fetus does not carry the antigen, intensive monitoring for hemolytic disease of the fetus and newborn (HDFN) is not required.
“Knowing whether the fetus has inherited the antigen targeted by a pregnant individual’s antibodies is a game-changer,” says Dr. Lani Lieberman, pediatric hematologist, and advisor to the project. “It helps avoid unnecessary anxiety in pregnancies where the fetus is not actually at risk.”
What the Test Does
Fetal blood group genotyping is a non-invasive prenatal test that uses cell-free DNA (cfDNA) from a pregnant individual’s plasma to determine the RhD status—and, in some cases, other red blood cell antigens of the fetus. By identifying the fetus’s RhD blood group, this test enables providers to tailor RhIG administration only to those who truly need it.
This approach can reduce unnecessary exposure to blood products, conserve limited RhIG supply, and enhance patient-centered care—all while maintaining protection against alloimmunization and HDFN.
For alloimmunized pregnant individuals, this testing allows health-care providers identify those at higher-risk, ensuring they receive close monitoring for signs of HDFN, while allowing those identified not at risk of alloimmunization to have routine care.
A Clinical Implementation Milestone
The launch of fetal blood group genotyping follows a rigorous evaluation by PSO’s multidisciplinary working group, which included Maternal-Fetal Medicine specialists, hematologists, laboratory medicine specialists, and patient partners. Testing is anticipated to be clinically available in fall 2025.
Training and support materials are available to help clinicians learn how to order the test, interpret results, and apply them to clinical care pathways. A detailed clinical protocol, requisition guides, and patient education resources will be available at www.prenatalscreeningontario.ca.
Why It Matters
RhD incompatibility has long been a concern in obstetric care. In cases where an RhD negative pregnant individual is carrying an RhD positive fetus, exposure to fetal blood can trigger an immune response, potentially affecting future pregnancies. For those truly at risk, RhIG remains an essential intervention. But for those not at risk, fetal blood group genotyping introduces a more efficient pathway.
“This is a meaningful change,” says Dr. Gwen Clarke, hematopathologist and advisor to the project. “It aligns with our commitment to evidence-based care and reflects the evolving expectations of both patients and providers.”
Health-care providers are encouraged to subscribe to PSO to stay updated on the rollout.
With fetal blood group genotyping now within reach, health-care providers have a new opportunity to deliver more precise, respectful, and resource-conscious care.
For up-to-date information, visit: www.PrenatalScreeningOntario.ca
Questions? Email: PSO@Bornontario.ca; Call: (613) 737-2281 / toll-free: 1 (933) 351-6490 to speak to one of our genetic counsellors or screening specialists.