Epidemiologic studies on maternal and pregnancy risk factors for autism spectrum disorder (ASD), including use of assisted reproductive technology (ART), found conflicting results. This study included the following aims: to assess frequencies of ART in a large ASD group; to examine confounding birth and familial risk factors in the ASD with ART group; to examine possible relationships between ART and autism severity, adaptive skills and developmental trajectory. The study included 624 participants, 507 diagnosed with ASD. Autism severity and adaptive skills were assessed using standardized tests. Extensive medical, familial and developmental histories were obtained. The rate of ART in the ASD group was significantly higher (10.7%) than in a large Israeli population (3.06%). Parental age's distribution did not differ in both ASD groups, with and without ART. Although maternal age was more advanced in the ASD group, the frequency of ART in young mothers (less than 29 years) was still significantly high (8.7%). The frequencies of gestational age less than 36 weeks and low birth weight (less than 2500 g) in the ASD with ART singleton group and in the Israeli population were not significantly different. None of the ASD with ART group and 14.7% in the ASD without ART group had a relative with ASD. Autism severity, adaptive skills and developmental regression were not significantly different in the ASD with and without ART groups. This pilot study points to the role of assisted conception as a risk factor for ASD. However, this group of ASD with ART does not represent a separate clinical phenotype in ASD. (Contains 3 tables.)