Autism prodrome 40 of 89
smoking, low Apgar scores at 1 and 5 minutes, gestational age at birth of less than 35
weeks, older parental age, and maternal psychiatric status of a past or current
psychiatric diagnosis as well as labor complications increase the risk rate for autism
(Glasson et al., 2004; Hultman, Sparen, & Cnattingius, 2002; Larsson et al., 2005;
Lauritsen, Pedersen, & Mortensen, 2005; Reichenberg et al., 2006).
Kolevzon et al. (2007) reviewed 7 independent investigations which all
involved large populations and identified parental age and obstetric conditions as risk
factors. Included in obstetric conditions are (1) low birth weight (LBW) and duration
of gestation and (2) intrapartum (during labor and delivery) hypoxia and fetal
hypoxia. Several obstetric variables may act as proxies of fetal hypoxia, including low
Apgar score, fetal distress, cesarean delivery, threatened abortion, and bleeding during
pregnancy. These conditions are mostly present in preterm babies and therefore in the
next section we specifically address premature birth as associated with ASD.
Low birth weight is of special interest because it is accurately measured and
associated with a range of cognitive deficits and psychiatric outcomes, including
problems related to speech and language, internalizing behavior problems, attention,
social skills, hyperactivity, and learning disabilities There is also a substantial
literature base on the relationship between LBW and lower intelligence (Casey,
Whiteside-Mansell, Barrett, Bradley, & Gargus, 2006). Prematurity and low birth
weight have been identified in numerous studies as a risk factor for ASD (Eaton,
Mortensen, Thomsen, & Frydenberg, 2001; Hultman, Sparen, & Cnattingius, 2002;
Larsson et al., 2005; Schendel & Bhasin, 2008; Williams et al., 2008). In a recent
study, parental reports on Extremely Low Birth Weight (ELBW) children were
compared to those of matched normal weight children with findings suggesting an
increase in symptoms pertaining to Autistic and Asperger's disorders at school age (as