Why do babies have an extrusion reflex?

Babies are born with different reflexes that help them survive the first months of life. Reflexes are involuntary actions that arise in response to certain stimuli.

The extrusion or tongue-thrust reflex helps protect babies from choking or aspirating food and other foreign objects and helps them to latch onto a nipple. You can see this reflex in action when their tongue is touched or depressed in any way by a solid and semisolid object, like a spoon. In response, a baby’s tongue will thrust out of their mouth to prevent anything but a nipple from a breast or bottle from coming through.

Read on to learn more about this and other reflexes.

When does the extrusion reflex develop?

While it’s not exactly clear when the extrusion reflex first develops in the womb, it’s present in most newborn babies. Tongue thrusting is important in the early months of a baby’s life because their muscles aren’t yet developed enough to swallow anything more than liquid.

This reflex works together with the sucking reflex, which develops between 32 and 36 weeks of gestation. The sucking reflex allows a baby to take in breast milk or formula from a breast or bottle.

How long does it last?

The extrusion reflex does go away with time. This is a normal part of development, and it starts to fade between 4 and 6 months after birth. This is also the age when babies generally start solid foods. The disappearance of the extrusion reflex helps babies start to wean from the breast or bottle, and learn to eat purees, cereals, or softened table foods.

Some children may display this reflex into older babyhood or childhood. When this happens, it may be a reason to speak with your doctor. If the tongue thrusting continues beyond infancy, it may cause issues with tooth alignment. It may also affect speech development, like creating a lisp while speaking.

How to test a baby’s extrusion reflex

Is your little one’s extrusion reflex still in action? You can test it by simply offering a spoon as if you’re trying to feed. The spoon can be clean or you may choose to add a small amount of baby cereal with breast milk or formula.

  • If a baby’s tongue thrusts forward and rejects the spoon, the reflex is still present.
  • If a baby’s mouth opens and accepts the spoon, the reflex may be fading or is already gone.

Extrusion reflex and solids

Experts recommend waiting until a baby is between 4 and 6 months old to introduce solid foods. Some groups, like the American Academy of Pediatrics and World Health Organization, are now setting the ideal time at 6 months old.

Before this point, the extrusion and gag reflexes are still strong. Each baby is different, so it’s important you follow your child’s individual signs of readiness to eat solids.

Your child may be ready for solids if they meet the following milestones:

  • holds head up independently
  • sits up in a high chair
  • opens mouth as spoon approaches
  • draws upper and lower lip inward when spoon is removed from mouth
  • weighing 13 pounds or more, and has doubled their birth weight

If your child meets these milestones and still doesn’t seem interested in solids, try again in a few days or a couple weeks.

If your baby’s extrusion reflex is still strong, it should fade by the time they reach 6 months of age.

Babies born prematurely may need to wait longer than the standard 4 to 6 months to start solids, whether or not the extrusion reflex is still present. Speak with your doctor.

In general, you may want to offer foods in a timeline that follows your child’s corrected age or age they would be if they were born on their due date. That means if a baby was born 3 weeks early, you would want to wait until they were between 4 months and 3 weeks, and 6 months and 3 weeks before offering solids.

Baby reflexes

There are several other reflexes you may notice in a newborn baby. These involuntary actions develop either in utero or are present at birth. They disappear by the time a baby reaches a few months to a couple years in age.

suckingBaby sucks when the roof of their mouth is touched; may also bring hand to mouthBy 36 weeks of pregnancy; seen in most newborn babies, but may be delayed in premature babies4 months
rootingBaby turns head when mouth is stroked or touchedSeen in most newborn babies, but may be delayed in premature babies4 months
Moro or startle Baby extends arms and legs, and throws back head in response to loud noise or sudden movementSeen in most term and premature babies5 to 6 months
tonic neckWhen baby’s head is turned to one side, the arm on the same side stretches out; the other arm bends at the elbowSeen in most term and premature babies6 to 7 months
graspBaby grasps when palm is stroked by object, like a caregiver’s fingerBy 26 weeks of pregnancy; seen in most term and premature babies5 to 6 months
BabinskiBaby’s big toe bends backward and toes splay when the sole of their foot is strokedSeen in most term and premature babies2 years
stepBaby “walks” or dances when held upright with feet touching a solid surfaceSeen in most term and premature babies2 months

The takeaway

The extrusion reflex is a normal part of a baby’s development and should fade over time as your little one reaches the middle of their first year.

If you have concerns about this reflex interfering with the introduction of solid foods, talk with your pediatrician. In many cases, your baby may just need a bit more time to learn this new skill.