Gestational age and the risk of autism spectrum disorder in Sweden, Finland, and Norway: A cohort study

Abstract

Introduction The complex etiology of autism spectrum disorder (ASD) is still unresolved. Preterm birth (<37 weeks of gestation) and its complications are the leading cause of death of babies in the world, and those who survive often have long-term health problems. Length of gestation, including preterm birth, has been linked to ASD risk, but robust estimates for the whole range of gestational ages (GAs) are lacking. The primary objective of this study was to provide a detailed and robust description of ASD risk across the entire range of GAs while adjusting for sex and size for GA. Methods and findings Our study had a multinational cohort design, using population-based data from medical registries in three Nordic countries: Sweden, Finland, and Norway. GA was estimated in whole weeks based on ultrasound. Children were prospectively followed from birth for clinical diagnosis of ASD. Relative risk (RR) of ASD was estimated using log-binomial regression. Analyses were also stratified by sex and by size for GA. The study included 3,526,174 singletons

Rates of Neuropsychiatric Disorders and Gestational Age at Birth in a Danish Population

“…Most previous studies 4 , 5 , 7 , 9 primarily focused on diagnosis in childhood according to 2 (term or preterm) or 3 (term, preterm, and very preterm) levels of classification regarding gestational age at birth. A few recent studies 18 , 28 , 29 , 30 have evaluated the heterogeneity of long-term neuropsychiatric risk among individuals born beyond 37 gestational weeks, reporting findings consistent with our results showing slightly elevated rates of neuropsychiatric disorders among the early term births. A recent study 14 has demonstrated that early term births born at 37 to 39 weeks might have poorer educational outcomes compared with those born at 39 to 41 weeks of gestation.…”

“…There has also been evidence on postterm delivery and mental health disorders. 17 , 18 , 31 However, unlike the Helsinki Birth Cohort Study, 17 , 31 we did not find elevated risks for other disorders associated with prolonged gestation except pervasive development disorders, specifically childhood autism.…”

“…For instance, children born within 37 to 41 weeks of gestation have traditionally been considered as a homogeneous, low-risk group, 13 but emerging evidence has indicated that children born at early term (37-38 weeks) had poorer cognitive outcomes, 14 lower educational achievement, 15 and higher rates of mortality 16 compared with those born at 39 through 41 weeks of gestation. Finally, some associations between postterm pregnancy (>42 weeks) and neurobehavioral 17 or mental health disorders 18 have been suggested, yet evidence remains inconclusive.…”

Postnatal Expression Profile of MicroRNAs Associated with Cardiovascular Diseases in 3- to 11-Year-Old Preterm-Born Children

“…The highest postnatal microRNA expression levels were observed in children born prematurely at lower gestational ages and in children born with lower birth weight. These findings may also contribute to the explanation of why preterm-born children with lower birth weight have an increased cardiovascular risk and to the explanation of the increase in cardiovascular risk with the decrease in gestational age at delivery [2,5,[9][10][11]15,19,20,22,23,26,27,29,31,35,39,43,44,51,58,59].…”

“…Besides, children and young adults born extremely preterm had significantly altered neuropsychological outcomes (lower general cognitive abilities, visuomotor skills, prospective memory, and aspects of executive functions and language) [32,57,58]. Gestational age of birth, including preterm birth, has also been observed to be associated with the risk of autism spectrum disorders [59].…”