The association of gestational age at birth with trajectories of early childhood developmental delay among late preterm and early term born children: A longitudinal analysis of All Our Families pregnancy cohort

Background Like infants born very preterm (<32 weeks), late preterm (=34 and <37 weeks) and early term (=37 and <39 weeks) births have been associated with increased risk of developmental delay (DD); yet, the evidence remains heterogeneous across the continuum of gestational ages, hindering early identification and intervention.Objective To estimate the association of gestational age at birth with early childhood trajectories of DD in early childhood for infants born=34 and <41 weeks, and determine how various maternal, pregnancy and infant characteristics relate to these trajectory groups.Methods Analysis of mother-child dyad data with infants born =34 and <41 weeks gestational age within an observational pregnancy cohort in Alberta, Canada, from 2008 to 2011 (n = 2644). The association between gestational age and trajectories of the total number of Ages and Stages Questionnaire domains indicating risk of DD from 1 through 5 years of age were estimated using group-based trajectory modelling along with other perinatal risk factors.Results Three distinct trajectory groups were identified: low-risk, moderate-risk (transiently at risk of DD in one domain over time) and high-risk (consistently at risk of delay in =2 domains over time). Per week of decreasing gestational age, the risk ratio of membership in the high-risk group increases by 1.77 (95% confidence interval [CI] 1.43, 2.20) or 1.84 (95% CI 1.49, 2.27) relative to the moderate-risk and low-risk respectively. Increasing maternal age, identifying as Black, indigenous or a person of colour, elevated maternal depressive symptoms in pregnancy, and male infant sex were associated with high- and moderate-risk trajectories compared to the low-risk trajectory.Conclusions In combination with decreasing gestational age, poor maternal mental health and social determinants of health increase the probability of membership in trajectories with increased risk of DD, suggesting that additional monitoring of children born late preterm and early term is warranted.