Fetal Erythroblastosis May Be an Indicator of Neonatal Transient Hyperinsulinism

Small for gestational age and birth asphyxia are associated with neonatal transient hyperinsulinism (THI). Some newborns with THI showed marked erythroblastosis on admission to our neonatal intensive care unit.

This study was designed to test our hypothesis that fetal erythroblastosis may be a risk factor for developing THI.

The records of all babies admitted to our neonatal intensive care unit within 24 h of birth between January 2010 and May 2014, and who were born after 34 weeks of gestation, were retrospectively reviewed. Hyperinsulinism was diagnosed as hypoglycemia concomitant with high serum insulin in babies requiring >6 mg/kg/min intravenous glucose and THI as hyperinsulinism without maternal diabetes or genetic disorders. The following three possible risk factors for THI were evaluated: (1) birth weight z-score, (2) 1-min Apgar score and (3) absolute nucleated red blood cell (aNRBC) count on admission.

Of 705 infants, 8 were diagnosed with THI. Multivariate logistic regression analysis revealed that the aNRBC count was the most significant risk factor for THI. The median aNRBC count was 181/µl (interquartile range 0-538/µl), and 8 of 71 infants (11.3%) having an aNRBC count >1,413/µl (90th percentile in this study) had THI. The aNRBC counts in the 8 cases with THI were significantly higher than those in the 5 cases with hyperinsulinism caused by maternal diabetes or genetic disorders.

This study showed that the aNRBC count was strongly associated with subsequent THI. Fetal erythroblastosis, characterized by chronic fetal hypoxia, may be an indicator of perinatal stress sufficient to cause THI.