Objective To examine the relationship between morphine exposure and growth of the cerebellum and cerebrum in very preterm neonates from early in life to term-equivalent age, as well as to examine morphine exposure and brain volumes in relation to neurodevelopmental outcomes at 18 months corrected age (CA). Study design A prospective cohort of 136 very preterm neonates (24–32 weeks gestational age) was serially scanned with MRI near birth and at term-equivalent age for volumetric measurements of the cerebellum and cerebrum. Motor outcomes were assessed with the Peabody Scales of Motor Development-2 and cognitive outcomes with the Bayley-III at 18 months CA. Generalized least squares models and linear regression models were used to assess relationships between morphine exposure, brain volumes, and neurodevelopmental outcomes. Results A 10-fold increase in morphine exposure was associated with a 5.5% decrease in cerebellar volume, after adjustment for multiple clinical confounders and total brain volume (P=0.04). When infants exposed to glucocorticoids were excluded, the association of morphine was more pronounced, with an 8.2% decrease in cerebellar volume. Morphine exposure was not associated with cerebral volume (P=0.30). Greater morphine exposure also predicted poorer motor (P<0.001) and cognitive outcomes (P=0.006) at 18 months CA, an association mediated, in part, by slower brain growth. Conclusions Morphine exposure in very preterm neonates is independently associated with impaired cerebellar growth in the neonatal period and poorer neurodevelopmental outcomes in early childhood. Alternatives to better manage pain in preterm neonates that optimize brain development and functional outcomes are urgently needed.

Infection is a risk factor for adverse neurodevelopmental outcome in preterm newborns. Our objective was to characterize the association of postnatal infection with adverse microstructural and metabolic brain development in premature newborns. One hundred seventeen preterm newborns (24–32 weeks gestation) were studied prospectively at a median of 32.0 and 40.3 weeks postmenstrual age: MRI (white matter injury, hemorrhage), MR (magnetic resonance) spectroscopy (metabolism) and diffusion tensor imaging (microstructure). Newborns were categorized as having “no infection”, “clinical infection”, or “positive-culture infection.” We compared brain injuries, as well as metabolic and microstructural development across these infection groups. In 34 newborns, clinical signs were accompanied by positive cultures while 17 had clinical signs of sepsis alone. White matter injury was identified in 34 newborns. In multivariate regression models infected newborns had brain imaging measures indicative of delayed brain development: lower N-acetylaspartate/choline, elevated average diffusivity (DAV) and decreased white matter fractional anisotropy. These widespread brain abnormalities were found in both newborns with positive-culture infection and in those with clinical infection. These findings suggest that postnatal infection, even without a positive culture, is an important risk factor for widespread abnormalities in brain. These abnormalities extend beyond brain injuries apparent with conventional MRI.

With improving survival rates of preterm newborns, adverse cognitive outcomes are increasingly recognized. Adverse cognitive outcomes are associated with decreased cerebellar volumes, and modifiable risk factors for these adverse outcomes should be identified. Animal models demonstrate reduced preterm cerebellar growth after exposure to glucocorticoids. Preterm neonates were prospectively studied with serial MRI examinations near birth and again near term-equivalent age. Adjusting for associated clinical factors, antenatal bethamethasone was not associated with changes in cerebellar volume. Postnatal exposure to clinically routine doses of hydrocortisone or dexamethasone were associated with impaired cerebellar, but not cerebral, growth. Modifying postnatal risk factors for impaired cerebellar development, and particularly glucocorticoid exposure, may help to decrease risk for adverse neurological outcome after preterm birth.