Autism spectrum disorder (ASD) is more prevalent in the population than ever before. It is debatable whether this is a real increase in incidence, a change in the diagnostic criteria, or both. The diagnosis is usually made by age 3 years; therefore, obstetricians and fetal-maternal specialists generally display limited awareness of the disorder. Unlike fetuses with chromosomal diseases, which have distinctive physical anomalies, some fetuses that eventually will develop ASD have minor physical anomalies. This is even truer in pregnant women who already have a child with ASD. Those fetuses have a 20 times higher risk of developing ASD than the general population. The more frequent minor physical changes that may be potentially detected by ultrasound are as follows: changes in head circumference (that become more noticeable after 6 months of age), the ratio between the second and the fourth digits, left handedness, and palatal changes. TARGET AUDIENCE: Obstetricians, Maternal - Fetal Medicine specialists, Pediatricians, Sonographers LEARNING OBJECTIVES: After completing this CME activity, physicians should better able to classify the increasing prevalence of this disorder, and to assess the minor physical changes in fetuses that some may be seen on ultrasound during pregnancy.