Extreme premature birth is not associated with impaired development of brain microstructure.

OBJECTIVE: To assess whether birth at <26 weeks gestation is an important predictor of brain microstructure maturation as determined by using diffusion tensor imaging. STUDY
DESIGN: We performed serial magnetic resonance imaging and diffusion tensor imaging in 176 infants born at <33 weeks gestation. Diffusion parameters were calculated for white and gray matter regions. Linear regression for repeated measures was used to assess the effect of extremely premature birth on brain maturation.
RESULTS: In white matter, fractional anisotropy increased by 0.008 per week (95% CI, 0.007-0.009; P < .0001) and mean diffusivity decreased by 0.021 mm(2)/sec per week, (95% CI, -0.24-0.018; P < .0001). Birth at <26 weeks was associated with lower white matter fractional anisotropy (-0.01; 95% CI, -0.018-0.003; P = .008), but this effect was eliminated when co-morbid conditions were added to the model. Moderate-severe brain injury was associated with decreased mean white matter fractional anisotropy (-0.012; 95% CI, -0.02-0.004; P = .002).
CONCLUSION: Brain microstructure maturation as measured serially in premature infants is independent of extremely premature birth. Brain injury and co-morbid conditions may be the important determinants of microstructure maturation.