Bringing a new life into the world is one of the most extraordinary journeys a person can take—and as an OB/GYN, it has been my life’s work and deep privilege to support families through this sacred transition. In our small, tight-knit community, where I’ve had the honor of delivering well over a thousand babies, I understand how important it is for patients to feel informed, safe, and supported every step of the way.
That said, I also know that some aspects of newborn care can be confusing, especially when information is gathered from many different sources. One topic that comes up more frequently these days is about newborn blood type, platelet counts, and rare conditions like neonatal alloimmune thrombocytopenia (NAIT). I’d like to take a moment to gently clarify how these are typically approached in medical care.
🤝 Clarifying a Common Question
Lately, I’ve had quite a few patients ask about newborn blood type testing, platelet counts, and conditions like Rh incompatibility or neonatal alloimmune thrombocytopenia. These are excellent questions, and I appreciate when families take an interest in understanding the care they and their babies receive.
It’s important to know that OB/GYNs are responsible for the health and well-being of the mother throughout pregnancy, labor, and delivery. Once the baby is born, a pediatrician or family medicine physician assumes responsibility for the newborn’s ongoing medical care. Each provider plays a specific role, and we work together to ensure the best outcomes for both mom and baby.
🩺 What Your OB/GYN Is Responsible For
During pregnancy and delivery, an OB/GYN’s primary responsibilities include:
- Monitoring the health of the mother and baby during pregnancy
- Managing labor and delivery
- Supporting the mother’s recovery during the immediate postpartum period
After delivery, the newborn is typically assessed by a pediatrician or pediatric nurse, who performs initial evaluations such as Apgar scores, physical exams, and any necessary interventions. From that point forward, ongoing medical care for the baby is handled by a pediatrician or family physician.
As the OB/GYN, I am the mother’s doctor. Once the baby is born, they have their own doctor who is specifically trained to monitor and manage the unique health needs of newborns.
🧬 Newborn Blood Type & Platelet Counts: What’s Routine, What’s Not
Many parents are understandably curious about their baby’s blood type, but it is important to know that testing a newborn’s blood type is not part of routine care. If the mother is Rh-negative and there’s a possibility of Rh incompatibility, testing may be warranted to guide appropriate care.
Mothers with a Rhesus negative (Rh-) blood type—a minority, as most individuals are Rh-positive—are typically offered a preventive injection (Rh immunoglobulin) at 28 weeks of pregnancy, or earlier if there are signs of bleeding, trauma, or other risk factors. This is a standard and evidence-based part of prenatal care. (See my article for more details – Understanding Rhogam and Its Role in Pregnancy – montanaobgyn.com.)
In the case of neonatal platelet disorders, such as Neonatal Alloimmune Thrombocytopenia (NAIT), routine testing is not performed unless there are clear risk factors—such as a history of a previously affected pregnancy. Even in these rare cases, diagnosis is usually made after birth, based on the baby’s symptoms and labs ordered by the pediatric team.
There is no standard medical practice that recommends determining a baby’s blood type during a routine pregnancy. Such testing would necessitate invasive procedures that carry significant risks to both mother and fetus.
Chorionic Villus Sampling (CVS) and Amniocentesis are two procedures that could be used to determine fetal blood type, but they are not performed solely for this purpose due to their invasive nature and associated risks.
Chorionic Villus Sampling (CVS): (https://montanaobgyn.com/understanding-chorionic-villus-sampling-cvs-what-expectant-mothers-need-to-know/)
- Procedure: Performed between 10 and 13 weeks of pregnancy, CVS involves inserting a thin needle through the mother’s abdomen or cervix to collect a small sample of placental tissue (chorionic villi). ACOG
- Risks: This procedure carries a risk of miscarriage, estimated to be slightly higher than that of amniocentesis. ACOG
Amniocentesis: (https://montanaobgyn.com/understanding-amniocentesis-what-every-expectant-mother-should-know/)
- Procedure: Typically conducted between 15 and 20 weeks of pregnancy, amniocentesis involves inserting a long, thin needle through the mother’s abdominal wall and into the uterus to withdraw a small amount of amniotic fluid surrounding the baby.
- Risks: The procedure carries a risk of miscarriage, infection, cramping, bleeding, and premature rupture of membranes.
Due to these risks, such invasive procedures are reserved for specific medical indications, such as diagnosing certain genetic conditions, and are not recommended for determining a baby’s blood type in a routine pregnancy. (https://montanaobgyn.com/screening-vs-diagnostic-tests-in-pregnancy-whats-the-difference/)
For more detailed information on these procedures and their associated risks, you can refer to the American College of Obstetricians and Gynecologists (ACOG) resources:
These resources provide comprehensive information to help expectant mothers make informed decisions about their prenatal care.
💛 Reassurance Through Evidence-Based Care
In routine pregnancies, there is no indication to determine a baby’s blood type before birth. Doing so would require an invasive test such as amniocentesis or chorionic villus sampling (CVS)—procedures that involve placing a needle through the mother’s abdomen and uterus to obtain amniotic fluid or placental tissue. These tests carry risks, including miscarriage, infection, and early rupture of membranes, and are only used when medically necessary for specific conditions.
Likewise, routine testing for platelet issues such as NAIT is not part of standard prenatal care unless there is a prior history or other clinical concern. These evaluations are generally done after birth if symptoms arise, under the direction of the pediatric team.
All medical decisions—including what tests are or aren’t done—are based on evidence, professional guidelines, and the specific needs of each patient.
If you ever have questions about what’s standard in pregnancy or newborn care, I encourage you to ask. I’m always happy to provide clarity, and I value open, informed conversations.
“Every decision made by your care team is grounded in compassion, clinical expertise, and a deep respect for your unique journey as a mother. Good care is never one-size-fits-all — it’s about making the right choices in the right moment, tailored to you and your baby. When taken out of context, medical decisions can be misunderstood — but in the moment, they are guided by what is safest, most appropriate, and most respectful of your experience.”