Introduction: Autistic Spectrum Disorder (ASD) affects 1% of children and it has been shown that one of its main causes is due to prenatal factors that affect the fetus during the gestational period. The objective was to estimate the prevalence of prenatal risk factors (RF) in children with ASD under 8 years of age who are monitored in a Children's Hospital.

Methods: A descriptive cross-sectional study was carried out. A survey was applied to the parents or guardians of the children during the wait for their control. A descriptive analysis of the data was carried out.

Results: 76 mothers of children with ASD participated. The male sex predominated, the average age was 5.4 years, the majority could speak without difficulty (78%) and 28% had a diagnosis of a chronic disease. The prevalence of prenatal RF found in this study is similar to that reported in other studies, especially the age of the parents, the years of maternal education, previous abortions and the diagnosis of diseases in pregnancy. However, the prevalence of factors such as high-risk pregnancy, maternal consumption of medicines during pregnancy, preterm delivery and tobacco and drug use during pregnancy were much higher in this study compared to other studies, and could be related to the diagnosis of ASD in childhood.

Conclusion: Based on these findings, a basis for comparative studies in the future is established.