Palmar grasp reflex

How it works

Stroke the palm of a newborn, or press a finger into it, and the fingers curl and grip. The grip is not gentle. Pull gently on the finger and the baby clings harder³. The same happens with the toes when the sole is pressed. That is the plantar grasp reflex³.

The reflex runs through the spinal cord and the lower parts of the brain. The cortex, the thinking part of the brain, is not yet in charge of the hands. It is present before birth and for the first three months, and fades away by five to six months¹. As the cortex matures it takes control of the hands and switches the reflex off. Grasping on purpose replaces it. The plantar version lasts longer and is usually gone by about twelve months³.

In 1891 the doctor Louis Robinson tested the grip in more than 60 newborns³. Most could hang from a rod by their hands for at least 10 seconds. One held on for 2 minutes and 35 seconds³. Nobody should repeat this. It shows how strong the reflex is, not that it is safe.

The reflex is one of a family called primitive reflexes. Others include rooting, which turns the head toward a touch on the cheek, and the Moro reflex, where a baby throws out its arms at a sudden drop or noise². Doctors check for them at newborn examinations. Their presence shows that the nervous system is working. Their disappearance on time shows that the brain is maturing².

How common it is

Every healthy, full-term newborn has this reflex, so there is no rarity to measure, though its strength can vary from baby to baby³. It is checked routinely at newborn examinations as one sign that the nervous system is working². Babies born early show the reflex the same way as babies born at term¹.

Is it a problem?

In a baby, no.

A doctor will want to look at a grasp reflex that:

• is missing at birth,
• is much weaker on one side,
• is still strong after about six months¹³.

In adults the reflex can return when the front of the brain is damaged, so doctors sometimes test the palm in older people².

History and culture

The reflex is sometimes called the Darwinian reflex, because it looks like a leftover from ancestors whose babies clung to their mother’s fur. Baby monkeys and apes do exactly this from birth¹. Whether the human reflex is truly a leftover, or simply a stage in learning to use the hands, is not settled.