Fetal ultrasound said short legs may be due to detection error, developmental delay, fetal malformation and so on. 1. Detection error: during pregnancy, you need to do regular pregnancy checkups, if the fetus has short legs during ultrasound, it may be caused by the measurement error of ultrasound examination, and you need to review it regularly. 2. Developmental delay: If the fetus is malnourished in the uterine cavity, resulting in growth and developmental delay, it may cause the fetus to appear short legs on ultrasound. 3. Congenital malformations: If the fetus has chromosomal abnormalities or is affected by various pathogenic factors such as medications and environmental factors, causing congenital developmental malformations in the uterine cavity, it may also appear short legs on ultrasound. Fetal ultrasound said short legs have more reasons, need to be under the guidance of a professional doctor for diagnosis and treatment.