Introduction: Introduction: Environmental exposures such as infections and maternal vitamin D levels follow seasonal patterns and affect fetal development especially brain development. Autism and learning difficulties are more common in children conceived in winter months. The effect of season of conception on neurodevelopment of preterm infants is unknown.
Objective: To assess impact of season of conception on neurodevelopmental outcomes at 21 months of corrected age in singleton infants < 29 weeks’ gestation.
Methods: Retrospective cohort study of infants < 29 weeks gestation born between January 2005 and December 2016 at a tertiary level NICU. Exclusion criteria included moribund infants and major congenital anomalies. Conception date was calculated as date of birth minus gestational age plus 14 days, and then divided into winter months (November - February) and non-winter months. The primary outcome was Bayley III composite score < 85 in any of the components, cognitive, language, or motor. Secondary outcomes included scores < 85 in individual components of the Bayley lll, death, hearing and visual impairment. Multivariate logistic regression analysis was used to assess the effect of confounders.
Results: Of the 493 infants eligible , 162 (32.8%) were conceived in winter. Table 1 shows maternal and neonatal characteristics . There was no difference between the two groups in the primary outcome and death (Table2 and 3). The median cognitive and language composite scores were significantly lower in the winter group (Table 2). The adjusted odd ratios of cognitive and language composite scores <85 were significantly higher in the winter group (Table 3).
Conclusion: Singleton infants <29 weeks gestation conceived in winter months have worse cognitive and language outcomes. Our results are consistent with the seasonal variation of increased infections and reduced ultraviolet exposure in the first trimester. Our observations may be of importance for public health.
Smita Roychoudhury– Senior Research Fellow, Section of Neonatology, Dept. Of Pediatrics, University of Calgary
Selphee Tang– Data Analyst, Section of Neonatology, Dept. Of Pediatrics, University of Calgary
Abhay Lodha– Associate Professor, Section of Neonatology, Dept. Of Pediatrics, University of Calgary
Belal Alshaikh– Clinical Assistant Professor, Section of Neonatology, Dept. Of Pediatrics, University of Calgary
Essa Alawad– Clinical Associate Professor, Section of Neonatology, Dept. Of Pediatrics, University of Calgary
Kamran Yusuf– Associate Professor, Department of Paediatrics University of Calgary