Vertical holding baby legs and feet blue may be caused by obstruction of blood flow, congenital heart disease and other reasons. 1. Obstructed blood flow: when holding the baby vertically, the adult’s arm is tighter, which may lead to the obstruction of blood flow in the baby’s legs, thus triggering the baby’s legs and feet to turn blue. It can be improved after adjusting the posture and does not require special treatment. 2. congenital heart disease: baby if there is congenital heart disease, such as congenital ventricular septal defect, etc., there will be lips, legs and feet, arms and other parts of the blue, purple and so on, vertical holding symptoms will be aggravated. Vertical holding the baby legs and feet blue may be caused by other reasons, if a long time does not get better, it is recommended to seek medical attention as soon as possible, under the guidance of the doctor targeted treatment.