Taking prenatal vitamins during the first month of pregnancy is associated with a lower risk of developing autism in children who are at high risk for the disorder, according to a new study. Researchers followed 241 children whose older siblings had a diagnosis of autism and who therefore had an increased risk of being diagnosed with the disorder. The researchers evaluated the children’s development starting at 6 months through 3 years of age. At the same time, the moms were asked through phone interviews and mailed questionnaires about prenatal vitamin use. Approximately 1 in every 4 children enrolled in the study went on to be diagnosed with autism spectrum disorder, similar to the rate of 1 in 5 for younger siblings of children with autism reported in prior studies.