The neonatal predictors of microcephaly, defined as a head circumference <5th centile in children born preterm, has not been systematically assessed. Children were drawn from the Developmental Epidemiology Network (DEN) cohort of very low-birthweight children (VLBW: 500–1500g) born from 1991 to 1993 at three sites in the USA. Neurological assessments were carried out among 198 singleton children (mean age 6 years 8 months, SD 0.5 years). Ninety-six children (48.5%) were male. Microcephaly was observed in 30 children (15%) and, using multivariate analysis, it was found to be associated with gestational age <26 weeks and bronchopulmonary dysplasia (BPD). Sonography-defined white-matter damage (WMD, i.e. echolucency or echodensities) was not associated with increased odds of microcephaly, while occurrence of intraventricular hemorrhage (IVH) was in univariate but not multivariate analysis. In analyses that excluded children with IVH/WMD, odds of microcephaly increased in dose-related fashion according to number of days on ventilator: >5 days, OR=4.5; 95%CI=1.4 to 15; >10 days, OR=5.7; 95%CI=1.7 to 19; >15 days OR=8.3; 95% CI=2.3 to 29.2. Among children without BPD, microcephaly was not associated with differences in IQ, while IQ scores among children with BPD or any ventilation were disproportionately lower among those with microcephaly. In multivariate analyses predicting IQ at age 7 years, microcephaly was found to modify the association between neonatal lung disease and IQ.
