A baby with a single umbilical artery is not necessarily a girl. A single umbilical artery can be seen in a boy or a girl, and it has nothing to do with male or female. Single umbilical artery means that the fetus has only one umbilical artery and one umbilical vein in the umbilical cord. In a normal state, there should be two umbilical arteries and one umbilical vein. The condition of single umbilical artery should be given special attention. The causes and pathogenesis of single umbilical artery have not been fully elucidated yet, and further research on the clinical significance is still underway. Usually, if a patient is found to have a single umbilical artery during a pregnancy test, he or she must be vigilant and needs to be closely monitored for abnormal fetal development.