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OBJECTIVES: The objective of the study was to evaluate the birth order of children with Autism Spectrum Disorder (ASD) and ways of delivery at birth, together with the phenomenon of reproductive stoppage and the number of siblings in the case families (families of children with ASD in the study).
METHODS: One hundred and ninety-six subjects with ASD and 54 healthy children were included into the study. Demographics were collected. Autism Behaviour Checklist (ABC), Aberrant Behaviour Checklist (AbBC), and Childhood Autism Rating Scale (CARS) were administered. Depending on the type of data and on the objective of the assessment, Mann– Whitney U-test, chi-square test, and Spearman tests were used for statistical analysis. A p-value smaller than .05 was considered to be statistically significant.
RESULTS: In the study group consisting of children with ASD, the rate of being the first-born child was determined to be more frequent, significantly, compared to the rate in the control group (p = .001). It was also found that 86.7% (n = 170) of the children in the ASD group had at least one sibling compared to the rate of 81.5% (n = 44) for their counterparts in the control group.
CONCLUSIONS: Our study compared ASD group to controls in terms of birth order, demonstrating a significant difference for being the first-born child in the ASD group. Birth order can be considered to be one of the several environmental factors that will help in understanding ASD, in which environmental factors can be the cause of phenotypic complexity. For all that, in our study, it was observed that having a child with autism in the Turkish sample did not affect the decision for the next pregnancy.