A relationship between maternal anxiety during pregnancy, known as antenatal anxiety, and negative child outcomes has been consistently shown in the literature. Children of mothers who experienced antenatal anxiety have higher rates of physical, behavioral, cognitive, and emotional deficits compared to children whose mothers did not experience clinical levels of anxiety during pregnancy. To date, research on antenatal anxiety and child outcomes is almost exclusively limited to non-clinical populations. Therefore, little is known about the relationship between maternal anxiety during pregnancy and suboptimal cognitive and behavioral development in children with disabilities. Families with fragile X syndrome (FXS) are a unique population with which to examine these relationships, as children with the full mutation have higher rates of problem behavior and cognitive deficits compared to typical children and mothers with the pre- and full-mutation are at an increased risk for developing psychopathology. The current study examines the relationship between maternal antenatal anxiety and child outcomes, specifically problem behavior, autistic symptoms, and HPA axis functioning in children with the full mutation. Results suggested that maternal antenatal anxiety significantly predicted child anxiety/depression. Current maternal anxiety was also predicative of child internalizing behaviors and attention problems. Implications of findings, limitations, and directions for future research are discussed