" Here’s something you can try at home if you are eight months pregnant or if you have a baby younger than 5 months old. If the infant has already arrived, place him on his back. Then gently lift up both of his legs, or both of his arms, and let them drop back to the bed of their own weight. His arms will usually fling out from the sides of his body, thumbs flexed, palms up, with a startled look on his face. This is called the Moro reflex. "

― John Medina , Brain Rules for Baby: How to Raise a Smart and Happy Child from Zero to Five