Startle Reflex in Babies: How Long Does It Last?

If your newborn is startled, they might cry out and curl up. This reflex is normal for the first few months of life. Here’s what else you need to know.

If your newborn is startled, they might cry out and curl up. This reflex is normal for the first few months of life and is something your baby’s doctor may check for after delivery.

If your new baby is startled by a loud noise, a sudden movement, or feels like they’re falling, they might respond in a particular way. They might suddenly extend their arms and legs, arch their back, and then curl everything in again. Your baby may or may not cry when they do this.

This is an involuntary startle response called the Moro reflex. Your baby does this reflexively in response to being startled. It’s something that newborn babies do and then stop doing within a couple of months.

Your baby’s doctor may check for this response during the postdelivery exam and at the first few scheduled checkups.

Types of newborn reflexes

Babies are born with a number of reflexes. Soon after birth, they can show reflexes for rooting, sucking, grasping, and stepping, among others.

Rooting

If you gently touch their cheek, your baby will turn their face, mouth open, toward your hand or breast. Babies do this instinctively to find food.

Sucking

Your baby will automatically begin sucking if something touches the roof of their mouth. Babies do this instinctively for nourishment. But although your baby naturally knows how to suck, it can take some practice to turn it into a skill.

If you’re having difficulty breastfeeding, don’t be discouraged. Instead, ask for help from a lactation consultant. You can find one through your local hospital.

Grasping

Your baby will close their fingers around something pressed into their hand, like your finger or a toy. This reflex helps babies develop the skills to intentionally grasp things as they grow.

Stepping

If you hold your baby upright and let their feet touch a flat surface, they’ll pick up one foot and then the other. It looks as though they’re trying to take steps. This reflex helps babies develop the controlled skill of walking, which they’ll probably start doing around their first birthday.

These reflexes are a normal part of a baby’s development. They help your baby function in the world. The Moro reflex is another normal baby reflex.

How can I keep my infant from getting startled?

You may notice your baby’s startle reflex when you’re trying to put them down to sleep. Leaning over to lay them down may give your baby the sensation of falling. It can wake your baby even if they’re sleeping soundly.

If your baby’s Moro reflex is keeping them from sleeping properly, try these tips:

Keep your baby close to your body when laying them down. Keep them close for as long as possible as you lay them down. Gently release your baby only after their back is touching the mattress. This support should be enough to prevent them from experiencing a falling sensation, which can trigger the startle reflex.
Swaddle your baby. This will make them feel safe and secure. Swaddling is a technique that mimics the close, cozy quarters of the womb. It can also help your baby sleep longer.

How to swaddle

To swaddle your baby, follow these steps:

Use a large, thin blanket. Lay the blanket out on a flat surface.
Fold one corner in slightly. Gently lay your baby face up on the blanket with their head at the edge of the folded corner.
Bring one corner of the blanket across your baby’s body and tuck it snugly beneath them.
Fold up the bottom piece of the blanket, leaving room for your baby’s feet and legs to move.
Bring the last corner of the blanket across your baby’s body and tuck it beneath them. This will leave only their head and neck exposed.

Your swaddled baby should only be laid on their back to sleep. Check them regularly to be sure they don’t overheat. If you have questions about swaddling, ask your baby’s doctor.

Encouraging movement

Your baby’s startle reflexes will begin to disappear as they grow. By the time your baby is 3 to 6 months old, they probably won’t demonstrate the Moro reflex any longer. They’ll have more control over their movements, and their reflexes will become less jerky.

You can help your baby progress by making time every day for movement. Give your baby space to stretch their arms and legs. This will help them tone and strengthen their muscles. Even newborn babies should have the opportunity to move, including their little heads. Just be careful to provide support to your baby’s head and neck when you’re holding them.

When to call your doctor

When a baby doesn’t have normal reflexes, it can be sign of potential problems. If the Moro reflex is lacking on one side of your baby’s body, it can be the result of a broken shoulder or a nerve injury. If the reflex is lacking on both sides, it might suggest brain or spinal cord damage.