Newborn babies are born with several important reflexes that help them through their first weeks and months of life. These reflexes are involuntary movements that happen either spontaneously or as responses to different actions. The sucking reflex, for example, happens when the roof of a baby’s mouth is touched. The baby will begin to suck when this area is stimulated, which helps with nursing or bottle feeding.

Reflexes may be strong in some babies and weak in others depending on a number of factors, including how early the baby was born before their due date. Read on to learn about the sucking reflex, its development, and other reflexes.

The sucking reflex develops when a baby is still in the womb. The earliest it develops is in week 32 of pregnancy. It’s generally fully developed by week 36 of pregnancy. You may even see this reflex in action during a routine ultrasound. Some babies will suck their thumbs or hands, showing that this important ability is developing.

Babies who are born prematurely may not have a strong sucking reflex at birth. They may also not have the endurance to complete a feeding session. Premature babies sometimes need some extra help getting nutrients via a feeding tube that’s inserted through the nose into the stomach. It may take weeks for a premature baby to coordinate both sucking and swallowing, but many figure it out by the time of their original due dates.

The sucking reflex actually happens in two stages. When a nipple — either from a breast or bottle — is placed in the baby’s mouth, they’ll automatically start sucking. With breastfeeding, the baby will place their lips over the areola and squeeze the nipple between their tongue and roof of the mouth. They’ll use a similar movement when nursing on a bottle.

The next stage happens when the baby moves their tongue to the nipple to suck, essentially milking the breast. This action is also called expression. Suction helps keep the breast in the baby’s mouth during the process through negative pressure.

Rooting versus sucking reflex

There’s another reflex that goes along with sucking called rooting. Babies will root around or search for the breast instinctually before latching on to suck. While these two reflexes are related, they serve different purposes. Rooting helps a baby find the breast and nipple. Sucking helps a baby extract breastmilk for nutrition.

You can test a baby’s sucking reflex by placing a nipple (breast or bottle), clean finger, or pacifier inside the baby’s mouth. If the reflex has fully developed, the baby should place their lips around the item and then rhythmically squeeze it between their tongue and palate.

Talk to your baby’s pediatrician if you suspect an issue with your baby’s sucking reflex. Since the sucking reflex is important for feeding, a malfunction with this reflex can lead to malnutrition.

Breathing and swallowing while sucking can be a difficult combination for premature babies and even some newborns. As a result, not all babies are pros — at least at first. With practice, however, babies can master this task.

What you can do to help:

  • Kangaroo care. Give your baby plenty of skin-to-skin contact, or what’s sometimes referred to as kangaroo care. This helps your baby stay warm and may even help with your milk supply. Kangaroo care may not be an option for all babies, especially those with certain medical conditions.
  • Wake for feedings. Wake your baby every 2 to 3 hours to eat. Your healthcare provider can help you determine when you no longer need to wake your baby for feeds. Premature babies may need to be fed more frequently, or woken to eat for a longer amount of time than other babies.
  • Assume the position. Hold your baby in a breastfeeding position even if they’re being tube-fed. You may even try soaking cotton balls with breastmilk and placing them near your baby. The idea is to get them to know the smell of your milk.
  • Try other positions. Experiment with holding your baby in different positions while nursing. Some babies do well in a “twin” position (or “football hold”), tucked under your arm with their body supported by a pillow.
  • Increase your let-down reflex. Work on increasing your let-down reflex, which is the reflex that causes milk to start flowing. This will make expressing milk easier for your baby. You can massage, hand-express, or place a warm heat pack on your breasts to get things flowing.
  • Stay positive. Try your best not to get discouraged, especially in the early days. What’s most important is getting to know your baby. With time, they should start to consume more milk over longer feeding sessions.

Lactation consultants

If you’re experiencing issues with nursing, a certified lactation consultant (IBCLC) may also help. These professionals focus solely on feeding and all things nursing-related. They can help with anything from latch issues to dealing with plugged ducts to assessing and correcting other feeding problems, like positioning. They may suggest using different devices, like nipple shields, to help promote better latch.

Your child’s pediatrician, or your OB-GYN or midwife, may be able to recommend a lactation consult. In the United States, you can find a IBCLC near you by searching the United States Lactation Consultant Association database. You may request home visits, private consultations, or help at a breastfeeding clinic. You can also rent equipment, like hospital-grade breast pumps. Some hospitals offer consultations for free while you’re on the maternity floor or even after you’ve gone home.

Babies develop several reflexes to help them adjust to life outside the womb. In premature babies, the development of some reflexes may be delayed, or they may retain the reflex for longer than average. Talk to your baby’s doctor if you’re concerned about their reflexes.

Rooting reflex

Rooting and sucking reflexes go together. Your baby will turn their head when their cheek or the corner of their mouth is stroked. It’s as if they’re trying to find the nipple.

To test for the rooting reflex:

  • Stroke your baby’s cheek or mouth.
  • Watch for rooting from side to side.

As your baby gets older, usually around three weeks of age, they’ll turn more quickly to the side that’s stroked. The rooting reflex usually disappears by 4 months.

Moro reflex

The Moro reflex is also known as the “startle” reflex. That’s because this reflex often happens in response to loud noises or movement, most often the feeling of falling backwards. You may notice your baby throwing their hands and legs up in response to unexpected noises or movements. After extending the limbs, your baby will then contract them.

The Moro reflex is sometimes accompanied by crying. It can also affect your baby’s sleep, by waking them up. Swaddling can sometimes help reduce the Moro reflex while your baby is sleeping.

To test for the Moro reflex:

  • Watch your baby’s reaction when exposed to loud noises, like a dog barking.
  • If your baby jerks their arms and legs out, and then curls them back in, this is a sign of the Moro reflex.

The Moro reflex usually disappears around 5 to 6 months.

Tonic neck

The asymmetrical tonic neck, or “fencing reflex” happens when your baby’s head is turned to one side. For example, if their head is turned to the left, the left arm will stretch out and the right arm will bend at the elbow.

To test for tonic neck:

  • Gently turn your baby’s head to one side.
  • Watch for their arm movement.

This reflex usually disappears around 6 to 7 months.

Grasp reflex

The grasp reflex allows babies to automatically grasp onto your finger or small toys when they’re placed in their palm. It develops in utero, usually around 25 weeks after conception. To test for this reflex:

  • Firmly stroke the palm of your baby’s hand.
  • They should grasp onto your finger.

The grasp may be quite strong, and it typically lasts until the baby is 5 to 6 months old.

Babinski reflex

The Babinski reflex happens when a baby’s sole is firmly stroked. This causes the big toe to bend toward the top of the foot. The other toes will also splay out. To test:

  • Firmly stroke the bottom of your baby’s foot.
  • Watch their toes fan out.

This reflex usually goes away by the time your child is 2 years old.

Step reflex

The step or “dance” reflex can make your baby appear to be able to walk (with assistance) shortly after birth.

To test:

  • Hold your baby upright over a flat, firm surface.
  • Place your baby’s feet on the surface.
  • Continue providing full support to your baby’s body and head, and watch as they take a few steps.

This reflex usually disappears around 2 months.

Reflexes at a glance

ReflexAppearsDisappears
suckingby 36 weeks of pregnancy; seen in most newborn babies, but may be delayed in premature babies4 months
rootingseen in most newborn babies, but may be delayed in premature babies4 months
Moroseen in most term and premature babies5 to 6 months
tonic neckseen in most term and premature babies6 to 7 months
graspby 26 weeks of pregnancy; seen in most term and premature babies5 to 6 months
Babinskiseen in most term and premature babies2 years
stepseen in most term and premature babies2 months

While babies don’t come with instruction manuals, they do come with a number of reflexes intended to help with their survival in the earliest weeks and months of life. The sucking reflex helps ensure your baby gets enough to eat so they can thrive and grow.

Not all babies get the hang of the sucking, swallowing, and breathing combination right away. If you’re experiencing nursing issues, reach out to your doctor or a lactation consultant for help. With practice, you and your baby will likely get the hang of things in no time.