330 The Association Between Preterm Birth and Autism Could be Explained by Maternal and Neonatal Morbidity

Department of Medical Epidemiology and Biostatistics, Karolinska Institute, PO Box 281, SE-171 77 Stockholm, Sweden.
PEDIATRICS (Impact Factor: 5.47). 10/2009; 124(5):e817-25. DOI: 10.1542/peds.2008-3582
Source: PubMed


We examined whether an association between preterm birth and risk of autistic disorders could be explained by pregnancy complications or neonatal morbidity.
This Swedish, population-based, case-control study included 1216 case subjects with autistic disorders who were born between 1987 and 2002 and 6080 control subjects who were matched with respect to gender, birth year, and birth hospital. We assessed associations between gestational age and autistic disorders and adjusted for maternal, birth, and neonatal characteristics. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs).
Compared with infants born at term, the unadjusted ORs for autistic disorders among very and moderately preterm infants were 2.05 [95% CI: 1.26-3.34] and 1.55 [95% CI: 1.22-1.96], respectively. When we controlled for maternal, pregnancy, and birth characteristics, ORs were reduced to 1.48 [95% CI: 0.77-2.84] and 1.33 [95% CI: 0.98-1.81], respectively. When we also controlled for neonatal complications, ORs were 0.98 [95% CI: 0.45-2.16] and 1.25 [95% CI: 0.90-1.75], respectively. Reductions in risks of autistic disorders related to preterm birth were primarily attributable to preeclampsia, small-for-gestational age birth, congenital malformations, low Apgar scores at 5 minutes, and intracranial bleeding, cerebral edema, or seizures in the neonatal period. Neonatal hypoglycemia, respiratory distress, and neonatal jaundice were associated with increased risk of autistic disorders for term but not preterm infants.
The increased risk of autistic disorders related to preterm birth is mediated primarily by prenatal and neonatal complications that occur more commonly among preterm infants.

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    • "The incidence of seizures in the first month of life (early life seizures ), a period identified as the highest risk for seizures in humans, is approximately 3 out of 1000 infants (Mizrahi, 1999), and can lead to adverse neurological and developmental outcomes including intellectual disability (ID) (McBride et al., 2000; Aldenkamp et al., 1999; Vanderlinden and Lagae, 2004). Autism spectrum disorders (ASD) and epilepsy are co-morbid, and early life seizures may increase the risk for autism (Buchmayer et al., 2009; Saemundsen et al., 2007; Saemundsen et al., 2008; Tuchman, 2009). About half of early life seizures are due to hypoxia, with the remainder due to stroke, other injuries and genetic causes (Vasudevan and Levene, 2013). "
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    • "This study aims to examine the relationship of a specific medical condition—namely, premature birth—with age of first concern. Premature birth has been indicated as a significant risk factor for ASD (Abel et al., 2013; Buchmayer et al., 2009; Dodds et al., 2011; Hultman, Sparén, & Cnattingius, 2002; Hwang, Weng, Cho, & Tsai, 2013; Larsson et al., 2005; Mamidala et al., 2013). Research has also indicated that children with ASD born prematurely may have more severe symptoms than those born later in gestation (Abel et al., 2013; Movsas & Paneth, 2012). "
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    • "However, epidemiological findings have not consistently found evidence of increased ASD risk with infection. For example, a California study of 407 ASD cases reported that hospitalization with infection was associated with increased risk (Zerbo et al., 2013), while a Swedish study of 1216 ASD cases found no such evidence (Buchmayer et al., 2009), In order to build the evidence base concerning prenatal infection and ASD risk, additional epidemiological studies are necessary. "
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