A Pilot Prospective Study of Fetomaternal Hemorrhage Identified by Anemia in Asymptomatic Neonates

BACKGROUND: Fetomaternal hemorrhage (FMH) is a poorly understood condition in which fetal erythrocytes transfer to the maternal circulation via a faulty placental barrier. Little is known about the true incidence, epidemiology, or pathophysiology of FMH in the general pregnant population as existing studies are based on retrospective cohorts and manifest diagnosis and selection bias. OBJECTIVE: To evaluate the practicability of a prospective study of fetomaternal hemorrhage in the general population based on antepartum maternal blood testing and neonatal anemia. STUDY DESIGN: Prospective cohort study. RESULT: Nineteen pregnant women were enrolled prior to the term delivery of twenty well infants. Five neonates were unexpectedly anemic on first postnatal testing. Antenatal maternal blood samples associated with 2 of 5 anemic newborns had positive Kleihauer-Betke testing while no newborn with a normal postnatal blood count had an associated abnormal Kleihauer-Betke test. CONCLUSION: Clinically significant FMH may be more common than previously thought. Prospective epidemiological study of FMH is feasible.