I didn’t know what maternal alloimmunization was until it changed my life. At nine weeks pregnant, my routine antibody screen came back positive for anti-Kell antibodies with a titer of 1,024. My obstetrician had practiced medicine for roughly thirty years and had never seen a case like mine. He explained what he could, but I left without understanding how much risk my baby faced, what my care should look like, or how quickly fetal anemia could develop. I went home, searched online, and found almost nothing.

I was referred to maternal-fetal medicine specialists, but over the next several weeks, I was still trying to educate myself and advocate for the care my baby needed. Lucy died just before 20 weeks’ gestation from severe fetal anemia and hydrops. Over time, I have had to process the heartbreaking realization that her death was almost certainly preventable. The diagnostic tools and treatment options already existed, but they were not offered to us in time.

After Lucy died, I was advised not to attempt another pregnancy. Instead, I found two maternal-fetal medicine specialists who understood anti-K HDFN and built a proactive plan for my next three pregnancies. Those pregnancies required close surveillance, early treatments to delay fetal anemia, and repeated intrauterine transfusions. All three of my Kell-positive children survived HDFN and are healthy today.

Why diagnostics are the foundation of HDFN management

Hemolytic disease of the fetus and newborn (HDFN) is a rare but serious condition that can develop when maternal red cell antibodies cross the placenta and target fetal red blood cells carrying the corresponding antigen. This can cause fetal anemia ranging from mild to life-threatening. Without timely care, hemolytic anemia can progress to hydrops, stillbirth, or neonatal death.

When a laboratory reports an antibody result, that result directly impacts the prenatal and neonatal course for that mother and her baby. Antibody identification, titer measurements, and antigen testing can help determine whether a pregnancy is at risk. Middle cerebral artery Doppler surveillance can screen for fetal anemia, and intrauterine transfusions can treat severe anemia before birth.

Some antibodies require different clinical responses. Anti-K is especially important because it can both destroy circulating fetal red blood cells and suppress fetal red blood cell production. Severe anemia can therefore occur at lower titers than with most other HDFN-associated antibodies. The 2025 clinical practice guideline identifies an anti-K titer of 4 as the threshold for beginning fetal anemia surveillance, compared with 16 for most other antibodies.

HDFN risk assessment and care initiation are extremely time-sensitive. The antibody must be identified and measured, its clinical significance understood, and the fetus’s antigen status determined before fetal anemia develops. If the fetus is antigen-positive or its status remains unknown, the result must be clearly communicated to the patient and translated by the obstetric team into an appropriate plan based on the specific antibody, titer, and pregnancy history. Laboratories are an essential link in this pathway. Accurate, timely testing provides the information clinicians need to guide surveillance, specialist referral, and treatment.

How increased awareness can change outcomes

The families who contact our foundation come from across the United States and around the world. Their circumstances differ, but we encounter the same breakdowns repeatedly: a positive result that was not fully explained, an antibody whose significance was underestimated, monitoring that began too late, or a patient who had to find specialty care on her own. These gaps are even harder to overcome for patients with limited access to experienced fetal specialists or crucial medical information.

In order to close the gaps in HDFN care, the tools and knowledge we already have must function as a connected care pathway. This is why our foundation and a diagnostics company are bringing laboratory expertise, current clinical guidance, and lived experience together to increase awareness and help ensure informed, timely care.

My own pregnancies show what this coordination can change. The anti-K antibodies that caused Lucy’s severe HDFN were still present during my next three pregnancies. Timely diagnostics, close monitoring, and expert clinical response made all the difference for my babies, as well as the hundreds of families our foundation has supported through their pregnancies. Every clinically significant antibody result should prompt a clear, evidence-based response from early pregnancy through the newborn period. We have many of the tools needed to change outcomes. Our responsibility now is to connect them and use them consistently.

Bethany Weathersby is a health care executive.