Perinatal Factors Associated with Autism Spectrum Disorder in Jamaican Children

Background: Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder with no well-defined etiology, mostly believed to stem from complex genetic-environmental interactions. Many environmental exposures during the crucial stages of neurodevelopment, which begins in the first few weeks of gestation and continues into early childhood, have the potential to contribute to ASD. Perinatal exposures such as mode of delivery and suboptimal characteristics at birth, including preterm birth and low birth weight as indicators of intra-uterine development, are thought to be associated with neurodevelopmental disorders such as ASD.

Objectives: To investigate the possible association of three perinatal factors, mode of delivery (cesarean vs. vaginal), low birth weight (<2500 gram), and preterm birth (before 37 weeks of gestational age) with ASD in Jamaican children.

Methods: We used data from the Epidemiological Research on Autism in Jamaica (ERAJ) and ERAJ-2 studies, which enrolled 343 pairs of age-(± 6 months) and sex-matched ASD cases and typically developing controls, collected during 2009-2018. We performed conditional logistic regression analyses to assess the possible association of each perinatal factor with ASD while controlling for potential confounders. Additionally, we explored potential interactions between the perinatal exposures and other covariates in relation to ASD in the multivariable conditional logistic regression models. Matched odds ratios (MORs) and their 95% confidence intervals (95% CIs) were calculated.

Results: Our findings suggest a significant unadjusted association between cesarean delivery and ASD [MOR (95% CI): 1.79 (1.23-2.60), P = 0.002]. In the multivariable analysis, we found that the parish of residence may be an effect modifier for the association between cesarean delivery and ASD in Jamaican children. Specifically, for children who lived in Kingston parish which has mainly urban residents, cesarean delivery was significantly associated with ASD after adjusting for the age of the parents at the child’s birth [adjusted MOR (95% CI): 2.34 (1.19-4.61), P=0.013], whereas this association was not significant for children from other parishes with a higher percentage of rural residents [adjusted MOR (95% CI): 0.94 (0.52-1.69), P = 0.824]. Additionally, although not statistically significant, the association between low birth weight and ASD appeared to be modified by car ownership of the parents as a measure of the household socioeconomic status (SES) in Jamaica, after adjusting for the age of the mother at the child’s birth [adjusted MOR (95% CI): 1.79 (0.89-3.64), P = 0.10 for low SES (i.e., families who did not own a car), and 0.64 (0.30-1.36), P = 0.248 for high SES (i.e., families who owned a car)]. Our findings do not support a significant association between preterm birth and ASD after adjusting for the age of the parents at the child’s birth and SES [adjusted MOR (95% CI): 1.21 (0.66-2.20), P = 0.539].

Conclusions: Our findings suggest that the parish of residence may be an effect modifier of the association between cesarean delivery and ASD in Jamaican children. Also, SES may be an effect modifier of the association between low birth weight and ASD in Jamaica. These findings require replication in future studies.