Developmental and neurologic sequelae of neonatal hyperviscosity syndrome.

One hundred eleven consecutive infants with neonatal hyperviscosity were identified by screening all newborns for polycythemia in an 18-month period. These polycythemic infants were matched with non-polycythemic newborns for birth weight, gestational age, Apgar scores, and sex. Maternal, intrapartum, and neonatal data were analyzed for associated morbidity. Maternal preeclampsia was more common among the hyperviscous patients than among control subjects. Hypoglycemia was also significantly increased among the hyperviscous patients. Follow-up studies at 1 to 3 years of age revealed a significantly higher incidence (38% vs 11%) of motor and neurologic abnormalities in the infants with neonatal hyperviscosity. The data suggested that concurrent hypoglycemia increased the risk of a poor outcome in hyperviscous infants inasmuch as 55% of infants with both characteristics were abnormal at follow-up. This, however, was not significantly different from the outcome of infants with hyperviscosity alone (P greater than .05 but less than .1). Further studies will be needed to confirm or deny this relationship.