“Dose Response” Relationship Identified by Large Swedish Study
Over 40 years of Swedish birth and health data has demonstrated a strong correlation between autism spectrum disorder (ASD) and premature delivery, according to a new analysis published in Pediatrics. This national cohort study used records from all 4,061,795 singleton infants born in Sweden between 1973-2013, who survived their first year. The cohort was later screened for autism identification using nationwide outpatient and inpatient diagnoses through 2015. The average rate of autism in Sweden for those with a typical gestational age (39-41 weeks) at birth is 1.4%. However, the data analyzed in this study showed a dose-response relationship, meaning the earlier gestational age at birth, the higher the prevalence of autism. ASD prevalences by gestational age at birth were 6.1% for extremely preterm (22-27 weeks), 2.6% for very to moderate preterm (28-33 weeks), 1.9% for late preterm (34-36 weeks), 2.1% for all preterm (<37 weeks), and 1.6% for early term (37-38 weeks). The study’s authors speculate that the relationship between prematurity and autism could come from elevated inflammation, including in the central nervous system, which is experienced with prematurity. This hypothesis has merit as previous research has linked neuroinflammation to ASD.
