As part of a prospective study of severely jaundiced Zimbabwean infants, the relationship between maximum total serum bilirubin (TSB) concentration in the neonatal period and neurodevelopmental outcome at the corrected age of 4 months was studied. Fifty infants with a TSB of > 400 micromol/l (23.4 mg/dl) were enrolled and screened with a neonatal neurological examination (NNE). The cause of jaundice was low birth weight in 22 (44%), ABO incompatability in 8 (16%), sepsis in 8 (16%) and congenital syphilis (6%) in 3 infants. In 9 infants a cause could not be determined. At 4 months, 2 infants had died and 3 were lost to follow up, leaving 45 infants for the infant motor screen (IMS) at 4 months of age. Mean TSB in the neonatal period was 485 micromol/l (28.2 mg/dl), and 7 infants received an exchange transfusion. Mean TSB of the infants with an exchange transfusion was 637 micromol/l (37.2 mg/dl) (range 429-865 micromol/l (25-50.3 mg/dl)) and of the infants without transfusion 459 micromol/l (26.8 mg/dl) (range 400 740 micromol/l (23.4-43 mg/dl)) (P < 0.0001). The TSB was not associated with birth weight, gestational age, gender or head circumference of the baby. On the IMS, 6 of 45 (13.3%) infants scored abnormal, 6 (13.3%) suspect and 33 (73%) scored normal. Three of the six (50%) remaining infants who received an exchange transfusion scored abnormal on the IMS while only 3 of the 39 (8%) infants without exchange transfusion were abnormal.
Conclusion: More than 25% of infants with a TSB of > 400 micromol/l (23.4 mg/dl) scored abnormal or suspect at 4 months of age and half of these infants already showed irreversible neurological symptoms. All infants who scored abnormal or suspect on the IMS with bilirubin levels between 400 and 500 micromol/l (23.4 and 29.2 mg/dl) had haemolytic disease or were premature.