4-Month-Old Baby: Milestones and Development

October 25, 2022
 minutes read
Written by
Mandy Treeby
Chief Baby Sleep Consultant
Medically reviewed by
Elissa Gross, DO
Board Certified Pediatrician & Lactation Consultant

Your 4-month-old baby is developing so fast. Every day they’re growing, trying new things, and accomplishing major milestones. It’s so exciting, but it also can be hard to keep up!

To help you keep track of the 4-month milestones, we’ve compiled some expert insights and advice to answer common questions, including “What are 4-month-old milestones?” and “How much should a 4-month-old sleep?”


What Are the Milestones for a 4-Month-Old?

We’ve separated the 4-month-old milestones into development categories. Note that the emotional and communication milestones are all about engagement with you and the world around them. This is a special time – and a great time to engage them back. When your baby “talks” to you, it’s fun to respond with excitement and interest in what it is they’re telling you – this helps teach your baby how conversations work!

And don’t worry if your baby doesn’t “tick all the boxes” on the 4-month-old milestone checklist. Every baby is unique and develops at their own pace – trust us, your baby is perfect just the way they are and if you ever have concerns, it’s always best to discuss with your healthcare provider.

Growth and Physical Development: Steady and Strong

Your 4-month-old baby is probably continuing their fast pace of growth (about 1 to 1 ¼ pounds per month), but remember that a steady rate of growth is more important than any specific gains in weight or length.

Senses: Developing Distance Vision

The world around your baby is coming into focus, literally, as their distance vision steadily improves. They may start to recognize you and other familiar faces at a distance, and they can easily follow moving objects with their eyes from side to side.

A 4-month-old baby's color vision is also improving, so you may notice they favor shades of red and blue. Another source of endless visual fascination for your 4-month-old baby? Themselves! An unbreakable mirror is a great toy for infants this age, as they can see a wide range of colors and shapes as well as their own movements reflected back.

Language Skills:

Your 4-month-old's language skills are also developing, thanks to improved hearing and cognitive development. They may be able to mimic some of the rhythms, tones, and patterns of some of the words you speak to them, and their cries may sound different based on their various needs. It may sound like baby babble now, but your 4-month-old baby is building a solid foundation for later speech.

Movement: Almost on a Roll

Four-month-old baby movement is all about muscle control and hand-eye coordination. If you notice more and more objects making their way to your little one's mouth, that's because with their vision improving, they're able to do this more successfully — just be careful of what's within their reach. They can probably grab and shake toys and rattles now and may soon be able to pass objects from one hand to another.

Your baby is almost on the move! They’re still working on strengthening their back and chest muscles, and also working on holding their head up while on their tummy. Before long they’ll have the body strength to roll over from one side to the other.

4-Month Physical Milestones:

  • Holds their head up without support
  • Hold a toy
  • Swings their arms
  • Brings their hand to their mouth – and objects, too! (It’s alright to let your baby put safe, larger objects in their mouths – just nothing small that they can choke on. _
  • Pushes themselves up from their tummy

4-Month Emotional Milestones:

  • Smiling – and not just from gas!
  • Small chuckles - the full laughter will come later
  • Tracks you with their eyes, which means their attachment is growing!
  • Makes noise to get your attention because they’re starting to communication.

4-Month Communication Milestones:

  • Coos by making those adorable "ooo" and "ahhh" noises.
  • Replies with coos when you talk to them.
  • Turns at the sound of your voice.

4-Month Cognitive Milestones:

  • Opens their mouth when they're hungry.
  • Examines their hands - they're becoming more aware of their body now!

4-Month Sleep Milestones:

  • Begins to sleep for longer periods.

Can 4-Month-Olds Roll Over?

A big 4-month milestone for some is rolling over: it’s often around now that babies begin to rollover one way – that is, back-to-belly or belly-to-back. Most babies can roll over both ways by 6-months.

Should My 4-Month-Old Get a Check-Up?

Yes, it’s recommended 4-month-olds go to their pediatrician to ensure they’re growing well, to discuss their 4-month milestones, and for another round of vaccines. This is also a great time to discuss your baby’s sleep with your doctor – 4-months is a big milestone for your baby’s sleep.

If you’re getting ready to sleep train, maybe because you’re returning to work or just want to get sleep in check, download the Smart Sleep Coach by Pampers™ for a personalized sleep plan tailored to your baby.

The big 4-Month Sleep Milestone

You may notice leading up to 4-months that your baby is sleeping longer at night and less during the day. This is because their circadian rhythm is reaching maturity – a big 4-month milestone that often marks the start of longer sleep stretches and better rest.

What Is the Circadian Rhythm?

The circadian rhythm is your baby’s natural, biological sleep regulating process. It’s the internal system that helps them understand the difference between day and night and part of the total system that governs their sleep drive.

In fact, a 2007 medical study of found that nearly 30% of infants experience a sleep regression at four months, and one of the potential reasons they found was delayed development of circadian rhythms. !

How Do Routines Help 4-Month-Olds?

In addition to developing their circadian rhythms, 4-month-olds are also starting to understand patterns.

By developing a consistent bedtime routine at this age you can help your baby learn to recognize when it’s time for sleep, giving them the space to calm and soothe themselves to sleep. When you repeat a consistent routine night after night, it cues your baby that it’s time for bed. Soon they’re soothing themselves to sleep – and sleeping longer, too. It’s incredible, incredibly easy, and incredibly fun. Enjoy these quiet moments together. They’re precious.

A Brief Guide to a 4-Month-Old’s Sleep

Your baby’s sleep evolves and changes as they grow. To help you understand your baby’s sleep, as well as your 4-month old’s milestones, here is a quick guide to your 4-month-old’s sleep, including how much sleep a 4-month-old needs, how many hours of sleep a 4-month-old needs, and how many hours of sleep a 4-month-old needs during the day.

How Much Sleep Does a 4-month-Old Need?

Ideally a 4-month-old gets about 14.5 hours of sleep over a 24-hour period.

How Much Should a 4-Month-Old Sleep at Night?

About 10-12 hours.

How Many Hours Should a 4-Month-Old Sleep During the Day?

About 3.5-4.5 hours over 3-4 naps.

What is a 4-Month-Old’s Wake Window?

Babies this age have longer awake windows than younger babies. At this point most 4-month-olds are awake 1.5-2 hours between sleeps. – but it’s okay if this varies for your baby.

How Long Should a 4-Month-Old’s Naps Be?

Anywhere between 30 and 90 minutes. Sometimes they may nap for up to 2 hours. At this age their circadian rhythms are maturing – a great 4-month-old milestone! – so their sleep will start to become more organized. That’s why this is a great time to start sleep training.

Is 4-months Too Early to Nap Transition?

At 4-months most babies have gone from 4-5 naps a day to 3-4 naps a day – the next transition will likely happen at 5-months, when many babies transition firmly to three naps. Keep in mind, though, that your baby is unique and will nap transition at their own pace. You’ll soon understand your baby’s sleep patterns and know when they’re getting ready to celebrate another milestone.

Is There a 4-Month Sleep Regression?

Yes, many parents report a 4-month sleep regression but this is temporary and will pass in a few weeks.

What is the 4-month Sleep Regression?

Since your baby’s circadian rhythm has matured, this regression is really about a shift in patterns. They may start sleeping longer but waking up more often.

What are the Signs of Sleep Regression?

Regardless of when a sleep regression happens, common signs that your baby is experiencing a sleep regression include:

  • Your baby’s naps are shorter
  • Your baby is refusing to take naps
  • Your baby’s naps are longer, but night sleep is shorter
  • Your baby protests at bedtime
  • Your baby wakes up crying at night
  • Your baby can’t fall back to sleep after waking mid-sleep
  • Your baby is more fussy than usual around nap or bedtimes.

Why Sleep Regressions are Sleep Progressions:

We most often hear the term “Sleep Regression” when discussing these little sleep hiccups, but we like to think of sleep regressions as sleep progressions.

Looking at them this way reminds us that your baby is developing well - they are experiencing this “regression” precisely because they’re learning and developing new skills. That’s great news – and totally worth a few disrupted nights.


Important Milestones: Your Baby by Four Months, CDC.
Your Baby’s Developmental Milestones at 4-Months, UNICEF
“Association between delayed bedtime and sleep-related problems among community-dwelling 2-year-old children in Japan,” Journal of Physiological Anthropology.
“Sleep of 4-month-old infants: bedtime, night waking and sleep problems,” Institute of Behavioral Health.
“Developmental Milestones,” Pediatrics in Review.

How We Wrote This Article

The information in this article is based on the expert advice found in trusted medical and government sources, such as the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists. You can find a full list of sources used for this article below. The content on this page should not replace professional medical advice. Always consult medical professionals for full diagnosis and treatment.

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4-month-olds are developing physical and mental abilities. Physically, they can push themselves up, hold their heads, and swing their arms. In terms of communications and other developments, 4-month milestones include cooing in response to the sound of your voice, indicating when they’re hungry, tracking you with their eyes, and smiling more.

Almost anything safe - reading, going to the park, singing, playing with toys, baths - as long as it's with you or a trusted caretaker. This is about more than safety - your baby is learning about the world and how to engage it. By being present and enthusiastic in play and "talking," you're teaching them how to engage the world - plus it helps them feel loved and safe!

Some babies start to roll over either belly to back or back to belly around 4-months. The signs your baby is preparing to roll over include rocking side to side. By 6 months most babies can roll over both ways.

While together time is fundamental to your baby's development, independent play helps build attention span, creativity, and focus - plus it gives you a moment of "me time," too.

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