This study examined if mothers' with hyperemesis gravidarum (HG) (excessive nausea and vomiting) is associated with children's autism spectrum disorder (ASD) risk, and how this association is influenced by race, ethnicity, sex, exposure timing, and medication used to treat HG. Children exposed to HG in-utero had higher rates of ASD than unexposed children, and children exposed at first and second trimester of pregnancies were also more likely to develop ASD. There were no gender differences but HG was significantly associated with ASD risk in white and Hispanic children. The medications used to treat HG did not contribute to ASD risk. Therefore when mothers have a HG diagnosis, it may be beneficial for there to be enhanced surveillance of their children to facilitate an earlier diagnosis and intervention.