Perinatal factors were investigated in 53 low birth weight infants with minor neurodevelopmental dysfunction at 2-year follow-up and in 106 consecutive controls matched for gestational age and birth weight (within 100-gram intervals). The obstetrical history, as evaluated by the obstetrical optimality score, was significantly worse in the cases than in controls (obstetrical optimality score = 50.9 +/- 5.9 vs. 53.2 +/- 6.9, p = 0.019 by Mann-Whitney test). Multiple conditional logistic regression analysis showed that after adjustment for socioeconomic status and education of the mother, a low number (< 3) of prenatal visits, and a third trimester hemorrhage were the only antenatal factors significantly associated with an increased risk of minor infant neurodevelopmental impairment. Neonatal acidosis (pH < 7.2 in the first 24 h of life) and male gender were additional significant perinatal risk factors. Only a few antenatal and perinatal factors are correlated with subsequent minor neurodevelopmental impairment in low birth weight infants.