This reflex begins when the corner of the baby's mouth is stroked or touched. The baby will turn his or her head and open the mouth to follow and "root" in the direction of the stroking. This helps the baby find the breast or bottle to begin feeding.
The root reflex lasts until about 4 months of age; then it is replaced by voluntary turning of the head to the nipple.
The sucking reflex, like rooting, is an automatic survival action. Rooting actually helps the baby become ready to suck. When the roof of the baby's mouth is touched, the baby will begin to suck. This reflex begins at about the 32nd week of pregnancy and is not fully developed until about 36 weeks’ gestational age. Hence, premature babies may have a weak or immature ability to suck.
Babies also have a hand-to-mouth reflex that goes with rooting and sucking and may suck on fingers or hands. Sometimes the fetus can be seen sucking his or her thumb on a prenatal ultrasound.
The Moro reflex is often called a startle reflex because it usually occurs when a baby is startled by a loud sound or movement. In response to the sound, the baby throws back his or her head, extends out the arms and legs, cries, then pulls the arms and legs back in toward the body. Even a baby’s own cry can trigger this startle reflex. This reflex lasts until 2 months of age.
Tonic Neck Reflex
The tonic neck reflex is often called the “fencing” position. When a baby’s head is turned to one side, the arm on that side stretches out, and the opposite arm bends up at the elbow. The tonic neck reflex lasts about 5 to 7 months.
Stroking the palm of a baby's hand causes the baby to close his or her fingers in a grasp. It is a strong reflex and is an even firmer grip in premature babies. The grasp reflex lasts 5 to 6 months.
When the sole of the foot is firmly stroked, the big toe bends back toward the top of the foot and the other toes fan out. This is a normal reflex up to about 1 year of age.
This reflex is also called the walking or dance reflex because a baby appears to take steps or dance when held upright with his or her feet touching a solid surface. This reflex disappears at 2 months of age.