Baby stiffens legs when trying to sit

baby stiffens legs when trying to sit

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During the first few months, babies learn how to use their muscles and joints, from crawling to sitting to walking.

Stiffening is a movement that babies can use to express a variety of emotions and needs, sometimes it is a reflex that they don’t have control over.

When they’re excited or frustrated, they’ll sometimes stiffen their bodies. They may stiffen their arms, legs, abdomen, or all at once, depending on the cause.

A baby stiffens his or her legs when trying to sit for a number of reasons. So, let’s get to it!

What make Babies Stiffen Their Legs?


Don’t Want to Go Where You Want Them to Go

Most babies stiffen their legs when you put them somewhere they don’t want to be. Some babies may decide they don’t like their car seats or being placed on the floor.

As a result, they’ll stiffen their legs to prevent you from putting them in those dreaded places.

baby sitting

If They Have Cerebral Palsy

Cerebral palsy (CP) is a group of neurological disorders that affect an individual’s movement, coordination, and posture. It can occur when a baby’s brain doesn’t develop normally in the womb or when it’s damaged during childbirth.

Leg stiffness when being picked up is one symptom of cerebral palsy in babies. So, if your baby has cerebral palsy, it explains why his or her legs stiffen.


Hypertonia is a condition characterised by abnormally increased muscle tone. It especially affects a baby’s neck, arm, and leg muscles.

This condition can be caused by a variety of factors, including head injury and a lack of oxygen during childbirth.

Babies with hypertonia frequently struggle to move, have poor balance, and make stiff movements.

Erb’s Palsy

While it’s highly unlikely, the cause of a baby’s stiff legs can be Erb’s palsy. It’s a birth injury that damages brachial plexus nerves in the neck, which causes muscle weakness in the arm or shoulder.

This injury often occurs when a baby’s head and shoulders are pulled excessively during childbirth.

Shoulder Dystocia

Another type of birth injury is shoulder dystocia, which occurs when one or both of a baby’s shoulders become stuck inside the pelvis during birth.

Many factors, such as being in the wrong position or weighing more than 3.5 kilogrammes, can cause a baby’s shoulder to become stuck during childbirth.

Shoulder dystocia, like Erb’s palsy, is unlikely to cause leg stiffness.

Baby Stiffens Legs When Trying to Sit – How to Prevent

Rule Out Health Concerns

The most common reason babies may stiffen their legs when trying to sit is that they don’t want to sit down. 

A quick Google search may tell you otherwise, but your baby will have been diagnosed at one of his or her checkups if they suffer from any illnesses, we’ve previously mentioned.

Given how straightforward the most common cause is, it’s frequently overlooked. So there’s no need to worry. It’s possible that your baby is just going through a phase.

If They Want to Stand, Help Them Stand

If your baby refuses to sit, you can help him or her learn to stand and strengthen leg muscles by placing him or her in a baby bouncer jumper or a door bouncer. This device can encourage babies to walk while also keeping them entertained with toys.

Keep in mind that babies shouldn’t be placed in baby bouncers until they’ve developed neck stability and head control, which is usually around five to six months old.

What’s more, if used frequently, baby bouncers can cause a delay in walking. As a result, you should limit baby bouncer sessions to 15 to 20 minutes and no more than two sessions per day.

Let Them Sit More Comfortably

It’s likely that your baby is stiffening his or her leg because the seat or the floor is uncomfortable. You can get your child a baby seat that’s made to provide babies with the utmost comfort.

You can also place your baby on cushions made specifically for babies, which should be comfortable enough.

Leave This Action for a While

Babies can be stubborn, which is completely normal as they go through many developmental stages. 

As a result, it may be best for some parents to leave their babies in their current position and stop trying to force them to sit somewhere else.

The situation can escalate, and your baby may develop colic, which occurs when a baby cries excessively for no apparent reason.

In Conclusion

If your baby stiffens his or her legs when trying to sit, it’s most likely nothing to be concerned about.

Babies exhibit a variety of unusual behaviours that may appear alarming but are entirely normal, such as throwing themselves backwards when upset.

Your baby may just want to stand or sit somewhere else more comfortable. However, leg stiffness caused by a disorder or an illness is highly improbable.