The Moro reflex may be a survival instinct to help the infant cling to its mother. If the infant lost its balance, the reflex caused the infant to embrace its mother and regain its hold on the mother's body. The Moro reflex might also be an alarm signal from the baby who is about to lose support, and the spread arms provide extremities for where to be grabbed by its handler to prevent a fall. https://en.wikipedia.org/wiki/Moro_reflex