Age-Dependent Associations Between Gestational Age and Clinically Recorded Sleep Problems in Early Childhood: A Population-Based Cohort Study.

AIM: To examine associations between gestational age (GA) and clinically recorded sleep outcomes at 6 months, 2 years and school entry. METHODS: This population-based study included 56 856 children. Sleep data from routine health examinations at 6 months, 2 years and school entry were linked to the Medical Birth Registry of Norway. Non-satisfactory sleep, difficulties initiating sleep and night awakenings were recorded during routine consultations. Associations between GA and sleep outcomes were examined using logistic regression analyses. RESULTS: The prevalence of non-satisfactory sleep was 22.4%, 15.1% and 11.6% at 6 months, 2 years and school entry, respectively. Each additional week of GA was associated with higher odds of non-satisfactory sleep at 6 months (adjusted OR 1.06, 95% CI 1.04-1.07). At 2 years and school entry, each additional week of GA was associated with lower odds of non-satisfactory sleep (adjusted OR 0.97, 95% CI 0.96-0.99 and 0.95-0.98, respectively). Few associations were observed between GA and the other sleep outcomes, except for night awakenings at 6 months and difficulties initiating sleep at 2 years. CONCLUSION: Increasing GA was associated with lower odds of non-satisfactory sleep at age 2 years and at school entry, whereas the opposite association was observed at 6 months. Sleep difficulties in children born preterm should remain a focus beyond infancy.