The clinical characteristics and outcomes of pregnancies at risk of hemolytic disease of the fetus and newborn (HDFN) in Sweden, Finland and Denmark were analyzed in a study recently published in AJOG Global Reports.
Although, theoretically, prenatal screening and treatment advances have reduced HDFN severity in many cases, there is scarce large-scale data on regular changes in outcomes.
To address this gap, the authors used national health registries, identifying over 32,000 pregnancies between 1997 and 2021 in which mothers were monitored for RBC alloimmunization or gave birth to infants with HDFN. Researchers analyzed factors that could affect the disease course, including delivery methods and neonatal health indicators like gestational age, birth weight and long-term diagnoses.
Pregnancies were categorized as HDFN or non-HDFN, and neonatal outcomes were further stratified by treatment type: intrauterine transfusion (IUT), neonatal transfusion, phototherapy or unknown treatment.
Results showed that HDFN pregnancies were more often associated with older maternal age, higher parity and increased rates of caesarean delivery compared to non-HDFN pregnancies.
Despite similar rates of stillbirth and maternal complications, a significant proportion of neonates from HDFN pregnancies required treatment—27% in Sweden, 38% in Finland and 12% in Denmark. IUT and neonatal transfusion groups had notably lower gestational age and birth weight, and higher neonatal unit admission rates (up to 94%) than non-HDFN neonates.
Interestingly, Denmark and Finland had more cases of HDFN pregnancies than Sweden, despite being half its size. The authors hypothesized that the difference could be due to more intensive screening and neonatal monitoring in those two countries.
Additionally, neonates receiving IUT or transfusion exhibited higher risks of congenital anemia, infections and impaired physiological growth. While bilirubin mediated neurological damage ( kernicterus)) was rare, jaundice was common in the phototherapy group.
Long-term follow-up of children revealed elevated rates of nervous system disorders and hearing impairments among those treated with IUT or transfusion. However, overall long-term outcomes were generally similar to non-HDFN pregnancies.
“Neonates with HDFN, particularly those requiring IUT or neonatal transfusions, showed poorer outcomes at birth compared to those without HDFN. Further research is warranted to evaluate current clinical practice and to improve the outcomes of at-risk pregnancies,” the authors concluded.
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