Data from: Month of birth and risk of autism spectrum disorder, a retrospective cohort of male children born in Israel

Background: Increased incidence and prevalence of autism spectrum disorder
(ASD) over the last two decades have prompted considerable
efforts to investigate its etiological factors. We examined an association
between month of birth and ASD incidence. Methods: In a retrospective
cohort of male children born from January 1999 to December 2008 in a large
health organization in Israel (Maccabi Healthcare Services), ASD was
followed from birth through December 2015. Results: Of 108,548 boys, 975
cases of ASD were identified. The highest rates (10.3 and 10.2 per 1000
male live births) were recorded for children born in May and August, and
the lowest rates for February (7.6 per 1000 male live births). Among lower
socioeconomic status households, boys born in August were more likely
(OR=1.71; 95% confidence interval: 1.06 – 2.74) of being diagnosed with
ASD than children born in January. Significantly higher rates were not
observed for other months. Conclusions: In line with several previous
studies, we found modestly higher likelihood of autism occurrence among
male children of lower socioeconomic levels born in August.