4 Month Baby Development – What To Expect

The 4-month mark is another big milestone in your baby’s life. In fact, every month is a big milestone, so it is important to always celebrate. Sooner than you think, the baby will be walking, talking, and just simply growing up. So, you do not want to miss a thing.

Now, if you think your 4-month-old baby looks like a completely different child, you are not wrong and you are not imagining things. There are some major brain and physical developmental milestones going on at 4 months that make your baby appear completely different.

To start things off, at 4 months, your baby has already doubled their birth weight, and in some cases, may even be heavier than that. Their sleeping is more solid with very long stretches at night. If you are lucky, your baby is probably sleeping through the night. Also, you may have a more predictable schedule for naps, feedings, and bedtime.

4 Month Baby Development - What To Expect
Image Source: Wikipedia.org

Summary Of The Main Developmental Milestones

Movement Milestones

  • Be able to roll over from front to back
  • Sit with support
  • Try to bare their weight while standing on a flat surface
  • Able to hold toys such as a rattle
  • Be able to hold up their head and chest
  • Should try to push up on their elbows when laying on their stomach
  • Be reaching for objects with one hand
  • Easily coordinate seeing and movement
  • Easily follow objects moving from side to side
  • Bring hands to their mouth easily

Brain Milestones

  • Able to understand cause and effect
  • Understand object permanence
  • Improvement in the clarity of eyesight and should enjoy looking at more colors and objects
  • Should smile spontaneously and mostly at people
  • Enjoy playing, and at times react with negative emotions e.g. crying when playtime is over
  • Be able to mimic facial expressions such as smiling and frowning
  • Recognizing people at a small distance
  • Cries should be specific to what they want, e.g. hunger, sleep, boredom, frustration, etc.

Sleep Regression

This is a frustrating experience that may occur at 4 months. It does not happen to all parents, but a few parents encounter it.

After establishing a good sleep routine with your baby, you may suddenly start to notice the following.

  • Your baby is waking up more frequently at night
  • Your baby refuses to sleep or nap
  • Your baby’s irritability has increased

This is as a result of the 4th month “growth spurt,” in your baby’s body and brain. So, do not worry, there are ways to handle this.

Continue to be consistent with their routine and sleep patterns and even though it is difficult. Stick to this routine during the regression. Keep laying them down to sleep during the normal nap and sleep times as they had been established. Also, keep the bath time and storytimes as well.

With time, they will get over it and continue smoothly with the routine. If you change the routine due to the sleep regression, it may be difficult to set it up again later when the phase passes. This is why we advise sticking to the already laid out plan.

Arms And Legs

In the beginning, your newborn baby may have kept their hands and knees folded all the time, but now they seem straighter. Your baby will no longer be curled up into a ball.

By now they are probably putting their hands in their mouth all the time. It is normal at this age and part of their developmental progress. If you notice that they still look tired, keep massaging their feet and hands to make them feel better. 

Bowed legs

Most newborns normally have bowed legs. This is because they were in a curled-up position in the womb. The legs will probably stay bowed until they start to walk, so do not worry too much about this. It will go away with time.

You can help them straighten their feet by supporting them when they stand on your lap. This will help them make their leg muscles strong.

Soft Spot And Head Bulge

You have probably noticed that your baby still has a soft spot on top of their head and a small one near the back. These openings on the baby’s skull should not scare you at all.

They are covered by a tough membrane and they have two primary functions; they allowed their big head to pass through the birth canal and they also give the brain the space it needs to grow.

At 6 months, you will notice that the smaller fontanel begins to close. However, the bigger one will take anywhere between 12-18 months to clear up. When the baby cries, it is normal for these to bulge out, so, don’t go running to the doctor when it happens.

4 Month Baby Development - What To Expect
Image Source: Wikipedia.org


By the end of 4 months, you should be very excited to go into the 5th month, as more surprises await you. Your baby’s development must be monitored month by month to ensure they are healthy and progressing as required.