What reflex is demonstrated by a newborn throwing its arms out when startled?

The reflex demonstrated by a newborn throwing its arms out when startled is known as the Moro reflex. This reflex is an involuntary response that occurs when a baby feels a sudden loss of support or hears a loud noise. The reflex involves the baby extending their arms and legs and then quickly bringing them back in, almost as if they are trying to hold onto something. This reaction is thought to be an evolutionary response meant to protect the baby from potential threats.

In contrast, the rooting reflex occurs when a newborn turns its head and opens its mouth in response to stimulation on the cheek, helping in breastfeeding. The tonic neck reflex involves the baby turning its head to one side and extending the arm on that side while flexing the opposite arm, a posture sometimes referred to as the "fencing position." The grasp reflex occurs when an object is placed in the palm of a baby's hand, causing the baby to grasp it tightly. While these other reflexes play vital roles in a newborn's development, the specific behavior of throwing the arms out when startled aligns distinctly with the Moro reflex.