Helderman JB, O'Shea TM, Kuban KC, Allred EN, Hecht JL, Dammann O, Paneth N, McElrath TF, Onderdonk A, Leviton A. Antenatal antecedents of cognitive impairment at 24 months in extremely low gestational age newborns. Pediatrics. 2012 Mar; 129(3):494-502.