Baby Development: Your Baby’s 4th Month of Life

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Update Date 19/06/2020 . 5 mins read
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Your baby is now four months old! Where did the time go, right? By now, your small family has probably established a routine. You have also probably noticed that your life with your baby has become significantly easier to manage, compared to how it was during the initial months of their life. As they approach their 4-month-old baby development milestones, you will be able to play and communicate with your baby more. 

A lot of important milestones are scheduled to happen this month for your baby! Read on to learn more about your baby’s growth and development as they enter their fourth month of life.

How Your Baby is Growing

During this month, your baby will be growing rapidly. Four-month-old babies usually weigh twice more than they did at birth and will gain about 1 to ¼ pounds. Your baby will also start to grow longer. By the end of month four, you should expect your baby to grow 0.8 inches in length. 

However, it is important to keep in mind that these digits are just mere approximations. Several factors can influence a child’s growth:

  • How much they feed
  • Genes
  • Hormones

What if My Baby is Too Small for Their Age?

If you notice that your baby is not the same size as other babies then it usually is not a bad thing. Babies can grow at different rates. However, it is best to raise your concerns with your baby’s physician to make sure that they are growing healthily. 

If your baby is a bit chubby, then set aside your fears about obesity until they are ready to take in solid foods at around six months and onwards. Breastfed or formula-fed babies should never be denied feedings to lose weight. At this stage of their lives, babies should be given all the nutrients they need, including fat. 

Developmental Milestones 

Developmental milestones are skills that most children or babies can do at a certain age, which can offer insight into your child’s development. Doctors can also use these developmental milestones to determine if your baby is healthy or not. 

Here are some of the key 4-month-old baby development milestones.

Motor skills

In terms of physical and motor skills, your baby should be able to do more types of movement. A four-month baby may be able to do the following: 

  • Your baby will be able to hold their head up while in a sitting position mostly.
  • Your baby will be able to raise their head and chest while they are lying on their tummy.
  • Your baby will be able to roll from their front to their backs.


By this time, your baby’s eyesight will also be able to see things well if the objects are up close. This means that they will be most putting anything within their grasp inside their mouths. 

Social and emotional development

In terms of social and emotional development, you can expect your baby to become more and more adept at interacting with others. You can expect your baby to be able to do the following:

  • Respond to affection by smiling
  • Tries to ‘talk’ to someone by cooing or babbling
  • Recognize the caregiver’s voice and touch

During their fourth month, your baby will also begin to get used to routines. Your baby will know when it is time to feed based on the position you hold them in, or might flex their hips whenever you are changing their diaper.

Major Theories in the Field of Child Development

Feeding & Nutrition

The American Academy of Pediatrics (AAP) recommends that children of all ages, especially infants, should be given vitamin D to stay healthy. At age 3 to 5 months, your baby should be fed five to six times within 24 hours.

Is it Time for Solid Food?

By this time, you will probably be very excited to start giving your baby solid foods. Some moms introduce solid foods to their babies around the fourth month. However, experts recommend that moms breastfeed or formula-feed their babies until they are about six months old. 

During this stage, your baby will be able to get all the nutrients they need through breastmilk or formula milk. If you introduce solid foods into their diet too early, you are putting your baby at risk of becoming overweight

One of the 4-month-old baby development milestones is the beginning of teeth. This can be uncomfortable for your baby, so watch out for the signs of teething, namely:

  • Red and swollen gums
  • Being more irritable or fussier than usual
  • Excessive saliva or drooling
  • A tendency to bite or chew objects

Baby Care Tips

Once your baby hits the four-month mark, you can now try giving them breast milk in a bottle if you have been exclusively breastfeeding them until this point. Also, your baby still does not need to drink water yet. So feeding them with formula milk or breastmilk is more than enough for their nutrition at this stage.

Skin conditions like rashes or cradle caps may also start to come about during this month so make sure to use products that are unscented and gentle enough for your baby’s skin.

4-month-old baby development milestones


A four-month-old baby may be already sleeping throughout the night and spend around 4-6 hours napping during the day. However, if you find that there’s a shift in your baby’s sleeping patterns, then they may be experiencing “sleep regression.” Sleep regressions happen when your baby is going through a growth spurt. 

Take comfort in the fact that this period of irregular sleeping patterns is normal and only lasts for a few days.

Baby Health & Safety 

During their fourth month, your baby is scheduled to receive vaccinations namely:

  • Rotavirus oral vaccine
  • DTaP (diphtheria, pertussis, and tetanus) shot
  • Polio shot

Since your baby will pick up the habit of putting things in their mouth, it is best to keep small objects away from them to eliminate the risk of choking. Also, make sure to provide toys that will not cause any injury to your baby.

What Can I Do to Help my Baby Grow?

Your baby will be more responsive to playtime during this month. Playing also encourages the development of language and communication skills in your baby. During playtime, your baby will enjoy hearing from you reading aloud or singing to them. Other ways to encourage play are:

  • Placing your baby in front of a mirror. Watch them try to talk to their own reflection, or even smile at it.
  • Provide brightly colored toys, as your baby will be able to see vivid colors the best.

What to Watch Out For and When to See a Doctor

It is normal to have concerns about your child’s health and development, especially if they are showing signs or behaviors that seem abnormal. Consult your physician if:

  • Your baby does not recognize you
  • Your baby is unable to make eye contact
  • Your baby is not trying to talk or make noises with their voice
  • Your baby does not turn to you when you speak
  • Your baby is not startled by loud noises

Your baby’s fourth month of life is definitely a big milestone for both you and your baby. If you are observing any unusual behavior in your baby, or if you feel like they are not reaching the appropriate 4-month-old baby development milestones at this stage, then it is best to consult your baby’s pediatrician.

Learn more about Parenting here

Hello Health Group does not provide medical advice, diagnosis or treatment.

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