The relationship between nucleated red blood cell counts and early-onset neonatal seizures

OBJECTIVE: This study was undertaken to better define the timing of neurolo gic insult in neonates with early-onset seizures through evaluation of neon atal nucleated red blood cell levels. STUDY DESIGN: Medical records and the international Classification of Disea ses, Ninth Revision codes were used to identify all term neonates with neon atal convulsions who were delivered at our institution (January 1, 1990-Dec ember 31, 1995). Each neonate with early-onset seizures was matched to the next 3 neonates who met the following criteria: gestational age greater tha n or equal to 37 weeks, no early-onset seizures, birth weight greater than or equal to 2800 g, umbilical artery pH greater than or equal to 7.25, and a 5-minute Apgar score >7. Demographic characteristics, clinical factors, a nd mean initial nucleated red blood cell counts were compared between group s. RESULTS: During the 6-year study period, there were a total of 36,490 singl eton term deliveries of infants who were alive at birth. Forty-five (0.1%) of these neonates had early-onset seizures. Thirty neonates with early-onse t seizures met the inclusion criteria. Mean nucleated red blood cell counts (number of nucleated red blood cells per 100 white blood cells) for neonat es with early-onset seizures were significantly increased compared with tho se of control neonates (18.4 +/- 22.0 vs 4.6 +/- 4.5; P < .0008). CONCLUSIONS: Our findings are suggestive of the hypothesis that neurologic injury leading to early-onset seizures often occurs before the intrapartum period.