sentences:  Although this is sometimes referred to as the startle reaction, startle response, startle reflex or embrace reflex, most researchers see it as distinct from the startle reflex, and is believed to be the only unlearned fear in human newborns.The Moro reflex is present at birth, peaks in the first month of life, and begins to integrate around 2 months of age.It is likely to occur if the infant's head suddenly shifts position, the temperature changes abruptly, or they are startled by a sudden noise.