Prenatal risk factors, with special focus on gender distribution of neurodevelopmental and psychiatric conditions were analysed in first-degree relatives in a population-based group of young children with autism spectrum disorders (ASD). Multiple information sources were combined. This group was contrasted with the general population regarding data from the Swedish Medical Birth register. In the ASD group, information was also obtained at parental interviews focusing on developmental and psychiatric disorders in the family. Compared to the general population, fathers of children with ASD were older and parents more often of non-European origin. Mothers of children with ASD had an increased rate of antidepressant and psychoactive medication use, and of scheduled caesarean sections. Fathers and brothers of children with ASD had high rates of ASD including the broader phenotype. Mothers of children with ASD had high rates of depression and other psychiatric disorders. These findings, hypothetically, could reflect a different ASD phenotype and difficulties diagnosing ASD in females or be an example of the close genetic relation between ASD and other psychiatric disorders. The results suggest that, in clinical and research settings, the familial background in ASD should be reviewed with a broader approach, and not be restricted to "looking out" only for diagnoses and symptoms traditionally accepted as being part of or typical of ASD. The high rate of parents of non-European origin has been noted in many Swedish studies of ASD, but the reason for this association, remains unclear. (Contains 1 figure and 4 tables.)