Which reflex is expected to be present in newborns but should disappear by 4-6 months?

The Moro reflex, also known as the startle reflex, is an involuntary response observed in newborns that typically appears at birth and is characterized by a sudden, uncoordinated movement of the arms and legs when the infant feels a sensation of falling or hears a loud sound. This reflex is essential for assessing the neurological function and maturation of the infant's nervous system.

The Moro reflex usually disappears between 4 to 6 months of age as the infant's motor control and coordination improve. This disappearance is significant as it indicates developmental progress; as infants grow, they become more stable and secure, reducing their startle response.

In contrast, the other reflexes listed have different timelines for their presence and disappearance. The Babinski reflex, for instance, can be seen up to around 12 months, while the palmar grasp reflex fades around 6 months. The rooting reflex, crucial for feeding, also typically disappears around 4 months. Thus, the Moro reflex is uniquely marked by its early presence and subsequent fading between 4 to 6 months, making it the correct choice in this context.