The association of chorioamnionitis and early postnatal risk factors for white matter injury (WMI) and its effect on early brain development were determined in a study at University of British Columbia, Vancouver, Canada. Thirty-one (34%) of 92 preterm newborns (24-32 weeks gestation), studied at a median age of 31.9 weeks and again at 40.3 weeks gestation, were exposed to histopathological chorioamnionitis, and 26 (28%) had WMI. Chorioamnionitis was not associated with an increased risk of noncystic WMI (p=0.6) on MR imaging, and did not affect brain development (p>0.1) in early life or at term-equivalent age. Culture positive postnatal infections (Staphylococcus species) and hypotension requiring therapy were significant risk factors for WMI (p=0.03). WMI was associated with lower metabolic (N-acetylaspartate/choline) (p=0.009), and lower microstructural (WM fractional anisotropy) (p=0.01) development. Neonatal outcomes were similar in newborns with and without chorioamnionitis, but newborns with WMI were neurologically more impaired than those without. [1]

COMMENT. Postnatal infections, especially staphylococcal, and hypotension are associated with white matter injury (WMI) in the premature infant, and WMI affects early brain metabolism and development. In contrast to some reports, the above study shows that histopathological chorioamnionitis is not associated with increased risk of WMI or abnormalities of brain development. Focal or multifocal noncystic WMI is the most prevalent pattern of brain injury in premature newborns (Hamrick SE et al. 2004, cited by authors).

A previous meta-analysis report from UCSF demonstrates that chorioamnionitis is a risk factor for cerebral palsy and/or cystic periventricular leukomalacia in the term and preterm neonate [2]. Studies evaluating risk of cerebral palsy following maternal fever or infection were not included in the meta-analysis, a factor possibly accounting for the different conclusion vs the Canadian study.

In an editorial, Linda de Vries (Wilhelmina Children’s Hospital, Utrecht, the Netherlands) expands on measurement of cytokines in newborns with WMI, and the finding that chorioamnionitis with or without funisitis makes a very low birth weight infant more susceptible to hypotension at time of birth [3].