Background: Behavior and socioemotional development are crucial aspects of child development .
Methods: A total of 2505 children born at <27 weeks' gestation was evaluated at 18 to 22 months' corrected age between January 1, 2008 and December 12, 2012 (86% follow-up). The Brief Infant and Toddler Social and Emotional Assessment was used to evaluate behavioral and socioemotional problems.