Sex-specific effects of birth weight on longitudinal behavioural outcomes in children and adolescents

IntroductionPrevious cross-sectional studies suggest that birth weight (BW) affects the development of aggression-, social- and attention problems differently in boys and girls. We sought to test if these differences could be confirmed in a longitudinal study. MethodsThe Raine Study provided prospectively collected data on perinatal variables and repeated child behaviour checklist assessments from ages five to seventeen. We used linear mixed effects model to determine crude and adjusted relationships between BW and childhood behaviour at a conservative significance threshold. Sensitivity analyses included an age ten teacher assessment. ResultsData on behaviour, BW and sex, was available in 2269 participants. Male sex was associated with increased aggression problems at lower BW compared to females in the crude model ({beta}: -0.436, 98.3%CI: [-0.844, - 0.0253]), but not the adjusted model ({beta}: -0.310, 98.3%CI: [-0.742, 0.140]). Male sex was associated with increased attention problems at lower BW compared to females in both the crude model ({beta}: -0.334, 98.3%CI: [- 0.530, -0.137]) and the adjusted model ({beta}: -0.274, 98.3%CI: [-0.507, -0.0432]). Male sex was associated with increased social problems at lower BW compared to females in both the crude model ({beta}: -0.164, 98.3%CI: [- 0.283, -0.0441]) and the adjusted model ({beta}: -0.148, 98.3%CI: [-0.285, -0.00734]). ConclusionUsing repeated measures from ages 5-17 we were able to show a crude and adjusted male vulnerability to lower BW in the development of attention problems and social problems. We did not find a BW x sex interaction for the development of aggressive behaviour.