Perinatal and Neonatal Risk Factors for Autism: A Comprehensive Meta-analysis

Abstract

WHAT'S KNOWN ON THIS SUBJECT: Autism etiology is unknown, although perinatal and neonatal exposures have been the focus of epidemiologic research for more than 40 years. Although studies show that obstetrical and neonatal complications may increase autism risk, the specific complications and magnitude of effect have been inconsistent. WHAT THIS STUDY ADDS: Our study provides the first review and meta-analysis of all 64 studies of perinatal and neonatal risk factors for autism published through March 2007. abstract BACKGROUND: The etiology of autism is unknown, although perinatal and neonatal exposures have been the focus of epidemiologic research for over 40 years. OBJECTIVE: To provide the first review and meta-analysis of the association between perinatal and neonatal factors and autism risk. METHODS: PubMed, Embase, and PsycInfo databases were searched for studies that examined the association between perinatal and neo-natal factors and autism through March 2007. Forty studies were eligible for the meta-analysis. For each exposure, a summary effect estimate was calculated using a random-effects model. Heterogeneity in effect estimates across studies was examined, and, if found, a meta-regression was conducted to identify measured methodological factors that could explain between-study variability. RESULTS: Over 60 perinatal and neonatal factors were examined. Factors associated with autism risk in the meta-analysis were abnormal presentation, umbilical-cord complications, fetal distress, birth injury or trauma, multiple birth, maternal hemorrhage, summer birth, low birth weight, small for gestational age, congenital malformation, low 5-minute Apgar score, feeding difficulties, meconium aspiration, neonatal anemia, ABO or Rh incompatibility, and hyperbilirubinemia. Factors not associated with autism risk included anesthesia, assisted vaginal delivery, postterm birth, high birth weight, and head circumference. CONCLUSIONS: There is insufficient evidence to implicate any 1 perinatal or neonatal factor in autism etiology, although there is some evidence to suggest that exposure to a broad class of conditions reflecting general compromises to perinatal and neonatal health may increase the risk. Methodological variations were likely sources of heterogeneity of risk factor effects across studies. Pediatrics 2011;128: 344-355

Changes in Prevalence of Autism Spectrum Disorders in 2001–2011: Findings from the Stockholm Youth Cohort

“…Similarly, effects of changes in diagnostic criteria and the inclusion of outpatient data could not explain a considerable part of ASD prevalence increase in Denmark . Changes in potential risk factors for ASD, including pre-, peri-and neonatal factors (Gardener et al 2009(Gardener et al , 2011) may contribute to increased incidence. However, the contribution of many of these factors to the observed ASD increase has been arbitrated as minimal (Schieve et al 2011).…”

Co-occurrence of Autism and Asthma in a Nationally-Representative Sample of Children in the United States

“…We computed and generated BMI percentiles from reported weight and height, (''Growth Chart Training'') and included it as a categorical variable using categories of \5th, 5th-85th and 95th percentiles in our analysis. In addition to brain injury which has been identified as a significant risk factor for autism, we abstracted age, gender, and SES, which were important covariates for asthma and autism (Becker 2007;Gardener et al 2011;Largent et al 2012;Porter et al 2012). We coded gender and brain injury as dichotomous variables and age as a continuous variable.…”

Obstetrical Mode of Delivery and Childhood Behavior and Psychological Development in a British Cohort

“…Included variables were determined a priori based on previous literature: small for gestational age (SGA) (Guinchat et al 2012), gestational age at birth (Guinchat et al 2012), maternal high blood pressure/pre-eclampsia/eclampsia (Guinchat et al 2012), mother smoking more than 1 cigarette a day while pregnant (Kolevzon et al 2007), being the first born child (Guinchat et al 2012), bleeding or threatened miscarriage during pregnancy (Guinchat et al 2012), poverty, white ethnicity, maternal age (Guinchat et al 2012), maternal education, maternal depression (Gardener et al 2011) and maternal body mass index (BMI) (Gardener et al 2011).…”