Platelet count in healthy full-term Nigerian neonates

633 platelet counts are reported on 338 full-term healthy Nigerian babies aged 1 hour to 28 days. Platelet counts for the first week (207,000 +/- 72,000 cumm) are significantly lower (P less than .001) than in the subsequent 3 weeks (282,000 +/- 94,000 cumm). Platelet counts of 100,000-400,000/cumm during the first week and 100,000-450,000/cumm during the rest of the neonatal period include 95% of the respective age groups of Nigerian infants studied and these ranges can therefore be regarded as standard for healthy Nigerian neonates. Platelet counts in Nigerian neonates are essentially similar to those reported elsewhere but significantly higher than in Nigerian adults.