The sucking reflex comes naturally to most babies, and its key to helping them effectively drink formula or breastmilk. Here's what you need to know.

Learn more about the different types of newborn reflexes, what causes them, and more.

None of the studies included used pupil dilation for red reflex testing, as newborns and infants have smaller pupils, which may theoretically decrease the validity of the test.

Specifically, newborns have in-born reflexes which guide them to the breast and help with latching and sucking.

But compared to a red reflex test the benefits were marginal in terms of detecting treatment warranting ocular pathologies.

Very few people can resist smiling at a newborn baby — signaling positive emotions, such as joy and interest. Of course, this is especially true for new parents. One study found that new mothers ...