A growing body of literature points to a relationship between prenatal exposure to stress and an increased risk of autism spectrum disorders (e.g., Kinney, Munir, Crowley, & Miller, 2008). Mothers of autistic children report significantly more relationship conflicts and stressful life events during pregnancy compared to controls (Beversdorf et al., 2005; Ward, 1990). Inspection of medical records also reveals that mother of autistic children are more likely to experience obstetric complications (e.g., Burd , Severud, Kerbeshian, & Klug, 1999; Glasson et al., 2004). Two critical points during gestation appear to be especially critical: between months 5 and 6, and in the two weeks just before birth. Women who faced significant stress at either of these two times were especially likely to give birth to a child who would later receive an autism diagnosis (Kinney, Miller, Crowley, Huang, & Gerber, 2008; Torrey, Hersh, & McCabe, 1975).
The primary goal of the current research was to investigate in detail the relationship between retrospective reports of prenatal stress and autism. We compared the prevalence of self-reported stressors during pregnancy for mothers of children with autism and neurotypical controls. Additionally, we asked whether certain types of stressful events were reported more frequently by mothers of children with autism. A final question was whether the quantity or quality of stressful events was related to the severity of autistic behaviors.
Twelve mothers of male children (range = 3 and 6 years) with a medical diagnosis of autism participated (ASD). Data was also collected from mothers of 12 neurotypical males who were age-matched to the male children with autism (NT). Mother-child dyads visited the lab for one session. Mothers completed a modified version of the Childhood Autism Rating Scale (CARS) to assess the presence and severity of their child’s autistic symptoms. Next, the mother was asked to complete a self-report measure that included questions about family demographic information, child autism history, and events during pregnancy.
Consistent with previous research, we found that ASD mothers reported more stressors during pregnancy (M= 3.13) compared to NT mothers (M= 1.57). We further found that stressors related to pregnancy and health concerns were overrepresented in the ASD sample compared to the NT participants. Finally, the number of reported stressors during pregnancy was strongly correlated with children’s score on the CARS (r = .55) among ASD participants. In contrast, there was a substantially weaker relationship between stressors and CARS score for NT participants (r = .21).
The preliminary results support previous studies that have found a potential relationship between prenatal exposure to stress and an increased risk for autism. Our research extends this work by examining the occurrence of specific types of stressors. In our sample, health-related concerns appear to be largely responsible for the differences in reported stressors. Our results also suggest that the number of stressors experienced prenatally is related to the severity of autism. The biochemical pathways by which stress may undermine neurotypical development are considered.