Risk of autism spectrum disorders in low birth weight and small for gestational age infants.
OBJECTIVE
To examine the relationship between birth weight, gestational age, small for gestational age (SGA), and 3 of the most common autism spectrum disorder (ASD) subtypes.


METHODS
In this population-based case-control study conducted in Finland, 4713 cases born between 1987 and 2005 with International Classification of Diseases-diagnoses of childhood autism, Asperger syndrome, or pervasive developmental disorder (PDD), were ascertained from the Finnish Hospital Discharge Register. Four controls, individually matched on sex, date of birth, and place of birth, were selected from the Finnish Medical Birth Register for each case. Conditional logistic regression models were used to assess whether birth weight and gestational age information predicted ASD after controlling for maternal age, parity, smoking during pregnancy, and psychiatric history, as well as for infant's major congenital anomalies.


RESULTS
Very low (<1500 g) and moderately low (<2500 g) birth weight, very low gestational age (less than 32 weeks), and SGA increased risk of childhood autism (adjusted OR 3.05, 95% CI 1.4-6.5; 1.57, 1.1-2.3; 2.51, 1.3-5.0; and 1.72, 1.1-2.6, respectively). Very low and moderately low birth weight, very low gestational age, and SGA were also associated with increase in PDD risk (OR 3.44, 95% CI 1.9-6.3; 1.81, 1.4-2.4; 2.46, 1.4-2.3; and 2.24, 1.7-3.0, respectively). No associations were found between the perinatal characteristics and Asperger syndrome. The increased risks persisted after controlling for selected potential confounders.


CONCLUSIONS
The finding that low birth weight, prematurity, and SGA were related to childhood autism and PDD but not to Asperger syndrome suggests that prenatal factors related to these exposures may differ for these ASD subtypes, which may have preventive implications.
Department of Child Psychiatry, University of Turku, Turku, Finland. katja.lampi@utu.fi
Katja M
KM
Lampi
Liisa
L
Lehtonen
Phuong Lien
PL
Tran
Auli
A
Suominen
Venla
V
Lehti
P Nina
PN
Banerjee
Mika
M
Gissler
Alan S
AS
Brown
Andre
A
Sourander
D001724:Birth Weight; D016022:Case-Control Studies; D002648:Child; D002659:Child Development Disorders, Pervasive / Q000175:diagnosis* / Q000209:etiology; D002675:Child, Preschool; D002658:Developmental Disabilities / Q000175:diagnosis; D005260:Female; D005387:Finland; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007235:Infant, Premature, Diseases / Q000175:diagnosis*; D007236:Infant, Small for Gestational Age; D008297:Male; D012042:Registries; D012044:Regression Analysis; D012306:Risk; D012307:Risk Factors