“AUTISM” The many theories of Etiology – PRENATAL and PERINATAL EVENTS
Pre- and perinatal factors have been implicated as having some role in the development of Autism, although the evidence is somewhat contradictory and no factors have been consistently identified. Early studies of Pre- and perinatal factors, including maternal history, abnormal presentation, in labor, low birth weight, low Apgar score, and post-maturity ( birth after 40 weeks’ gestation ), suggested that they could have a minor role in the etiology of Autism ( Nelson, 1991 ). Studies have found increased risk of Autism associated with daily smoking in early pregnancy, maternal birth outside Europe and North America, cesarean delivery, low ratio of size to gestational age, 5-minute, Apgar score below 7, and congenital malformations ( Hultman, Sparen, and Cnattingius, 2002 ). Increased incidence was found in multiple births and in children of African descent ( Croen, Grether, & Selvin, 2002 ). Mothers of children with an ASD are more likely to report they had used prescription drugs during pregnancy, had a lengthy labor, had a viral infection, had abnormal presentation at delivery, or had an infant with low birth weight ( Wilkerson, Volpe, Dean, & Titus, 2002 ). It appears that no association exists between Autism and maternal diabetes, ( Hultman et al.,2002 ).
Other work supports an association between the development of one of the ASDs and complications in pregnancy, delivery, and the neonatal phase ( Juul-Dam, Townsend, & Courchesne, 2001 ). Mothers of children with an ASD are also more likely to report they had intrauterine stress ( Wilaerson et al., 2002 ). However, the specific events that carry the highest risk represent a variety of pathologic processes without a consistent unifying feature ( Juul-Dam et al., 2001 ).