Your 4-Month-Old Baby’s Milestones & Development

If it feels like your 4-month-old is a whole new baby at times, you’re not imagining things. The 4-month mark is a big milestone in your little one’s life, thanks to some major brain and physical development milestones. Most babies by this age will have doubled their birth weight (or weigh more) and will be sleeping longer stretches at night.

Your 4-month-old's vision is also drastically improving. "Your baby's visual range has increased to several yards, which is crucial in this period of rapid early motor and cognitive development," explains Florencia Segura, MD, FAAP, a pediatrician at Einstein Pediatrics in Vienna, Virginia. 

Being 4 months old comes with so many new, exciting achievements. From improved mobility to a more consistent sleep schedule and interest in solid foods, the developmental milestones at this age happen quickly—so it's important to keep up!

At This Age

  • Development: Your baby's vision is improving, they are becoming more sociable, and are beginning to reach and roll.
  • Sleep: Your baby is likely taking three to four naps a day. The dreaded 4-month sleep regression may make an appearance.
  • Food: Your baby is still getting plenty of breastmilk and/or formula every three to four hours.
4-month-old baby milestones and development
Illustration by Joshua Seong, Verywell

4-Month-Old Baby Development

Your 4-month-old baby is really starting to come out of their shell! You're likely noticing their budding personality and improved physical abilities.

At 4 months old, your baby has likely doubled their birth weight. Babies this age typically gain about 1 to 1¼ pounds and grow about 0.5 inches per month.

Your baby's developing vision allows them to track objects, and their increased neck strength helps them hold their head steady. They are able to sit upright with support and are able to follow moving things with their eyes from side to side. They also enjoy looking at more colors, shapes, and patterns.

Your baby's brain is also developing rapidly. "So many connections are made in your baby's brain during this time," says Dr. Segura. "These brain connections are being reinforced through a concept known as 'serve and return.' When your baby 'serves' you language by a smile, laugh, or coo, the parent 'returns' it with a smile, laugh, or acknowledgment."

Lyndsey Garbi, MD, chief pediatrician of Blueberry Pediatrics and a member of the Verywell Family review board, adds that 4-month-olds love to shake objects and bring them to their mouths. They are also likely to become fascinated with their feet at this age. You may notice that they are reaching for just about everything! This is because they are coordinating vision with movement—meaning that when they spot something they want, they are going to make a break for it.

4-Month-Old Baby Milestones

What a fun month this is with your baby! They are becoming much more active and interested in their surroundings. At 4 months old, babies start to become little social butterflies. They are big fans of experimenting with different sounds and their constant babbling is arguably one of the most adorable new skills! Dr. Garbi adds that you may also notice different cries based on their needs (hunger, pain, etc.).

It's also an exciting time—your baby recognizes familiar faces now! They are likely giving you (and other prominent family members and/or friends) a big smile when you walk into the room. They can also mimic certain facial expressions or sounds and respond to affection. You might even get that coveted first laugh.

Additionally, your 4-month-old is becoming more interested in exploring the world around them. "Your baby will consistently reach for rattles and objects now that their little hands are predominantly open (instead of a closed fist like during those first few months)," says. Dr. Segura. At this age, they are looking at their hands with interest and bringing their hands to their mouths.

Your baby should also be able to push up onto their elbows or hands during tummy time. They may even start rolling from belly to back and should be able to push down with their legs as you help them stand up on a flat surface. (This is a great way to build leg strength!)

Additional Behaviors

  • More interest in playing with people
  • Reaches for objects with one hand
  • Swings at dangling toys
  • Smiles spontaneously
  • Notices their reflection in the mirror
  • Bears weight when standing on a hard surface

When Should You Be Concerned?

If you notice your 4-month-old exhibiting any of the following behaviors, it's best to bring it up to your pediatrician:

  • Does not respond to or seem interested in your face
  • Does not smile
  • Has crossed eyes
  • Unable to hold their head up or sit with support
  • Does not watch people or items as they move
  • Has gained less than 50% of their birth weight

Remember that every baby is unique. Babies reach different milestones at their own pace, and your pediatrician will be able to assess your child's progress.

4-Month-Old Baby Food

At 4 months old, babies are usually still breastfed, bottle-fed, or a combination of both. They usually eat 4 to 6 ounces per feeding every three or four hours. To ensure they are getting enough food, keep an eye on their diapers. They should be having at least five to six wet diapers per day. If you notice your baby is making clicking sounds while sucking, working hard to breathe, or constantly spitting up or vomiting, it's important to reach out to your pediatrician.

As your baby starts sleeping longer stretches of time at night and taking more regular naps, expect a big change in how frequently they will want to nurse. However, your infant may still have periods when they will want to nurse more often, such as during a growth spurt or when they are sick.

Introducing Solid Foods

While breastmilk or formula is all your baby needs at this age, Dr. Garbi says that it is safe to introduce solid foods between 4 and 6 months. That said, you should always get the OK from your pediatrician before starting. Once you are given the green light, Dr. Garbi suggests only giving them soft foods they can mash with their gums. Introduce them one at a time and monitor for any allergic reactions. 

Many pediatricians advise baby-led feeding, which encourages parents to follow their own baby’s cues to know when the best time is to introduce solids. Some babies may be ready to try solid foods earlier (around 4 months) and some babies may not be ready until closer to 6 months. Every baby is different and it's important to avoid introducing solids too early.

According to the AAP, here are some signs your little one may be ready to start solid foods:

  • Holds their head up
  • Opens their mouth near food
  • Tries to move food from a spoon to their mouth
  • Has grown big enough (at least doubled their birth weight)

4-Month-Old Baby Sleep

In general, your 4-month-old needs 12 to 16 hours of sleep per day. "During the day, they will be taking four naps totaling an average of three to four hours of daytime sleep," says Dr. Segura. "The wake windows between these naps are between 1.5 to 2.5 hours."

Your baby may be getting a little older, but all of the same safe sleep practices still apply.  "It is recommended that babies sleep in their own bassinet or crib in a parents' room [for] up to 6 months minimum," explains Dr. Garbi.

If your baby has started rolling from their back to their tummy, Dr. Segura adds that it is okay for them to do so at night while they are sleeping. However, it is still important to place them in their crib on their back.

Sleep Regression

The dreaded 4-month sleep regression is likely to pop up at this time. All of a sudden, your expert sleeper is waking up at all hours of the night for reasons you can't quite figure out. It is certainly frustrating, but remember, you're not alone! This too is a phase that will pass.

Often, sleep regressions are the result of a “growth spurt” in your baby’s brain and body. This is temporary, so continue to be consistent with your baby’s routine and sleep patterns.

Some helpful sleep habits to keep in mind at this age include laying your baby down awake but sleepy. As your little one learns more about cause-and-effect this month, they may soon realize that by crying, their parents will come to pick them up. You might have to experiment more this month by teaching your infant to self-soothe or fall asleep on their own.

You can also allow pacifier use for naps and bedtime. The AAP still recommends pacifier use with naps and bedtime as it is associated with a reduced risk of SIDS.

4-Month-Old Schedule

In between naps and feedings, your baby is spending a lot of time exploring on their tummy. There are a variety of tummy time toys to help facilitate their cognitive, physical, and social development, including rattles, mirrors, musical instruments, sensory toys, and activity gyms. Soft blocks and books are also beneficial. Put your baby down on the floor or play mat, place a few toys in front of them, and encourage them to reach for the toys.

As you're hanging out, you can help your infant’s development by using a baby seat, holding them on your lap, or using a breastfeeding pillow propped behind them as they learn to sit. Of course, never leave your baby unsupervised near a pillow, especially as they develop those muscles needed to hold themselves up, because there will be a bit of toppling over that happens in the beginning!

Along with their growing interest in playtime, they may also begin to grow new teeth. Teething toys are incredibly helpful in soothing sore gums and crankiness. Your 4-month-old's schedule should also include a bedtime routine—it's the perfect time to start if you haven't yet. You can try a warm bath, some soothing cuddles, or a couple of songs.

"[At 4 months old], babies will continue to consolidate nighttime sleep, and a consistent bedtime routine will help your baby wind down at the end of the day," adds Dr. Segura.

4-Month-Old Baby Health and Safety

It's time for your baby's 4-month well visit!  At this appointment, they will receive all of the same vaccines they received at the 2-month visit. These include second doses of the pneumococcal, DTaP, Hib, polio, and rotavirus vaccines.

Along with the physical examination at your 4-month well visit, your pediatrician will discuss your baby's feeding and sleep schedule, how your baby is growing, and any concerns you might have.

Sleep Safety

At this age, you should still be following AAP guidelines for preventing sudden infant death syndrome (SIDS). They should sleep on their backs on a flat surface without any toys, pillows, blankets, loose bedding, or bumper pads to avoid suffocation. Your 4-month-old should only be brought into your bed for comfort or feeding, as the AAP does not recommend bed-sharing for any baby.

Car Seat and Home Safety

Dr. Garbi explains that your 4-month-old should continue to stay in a rear-facing car seat that is securely fastened, and to avoid wearing jackets while in the seat. She also recommends you start babyproofing your home in preparation for them becoming more mobile in the next few months. This includes adding childproof locks where needed, covering sharp edges on furniture, and covering electrical sockets.

Colds

Many babies can have runny noses with green or yellow discharge, but not have an actual sinus infection. Green-colored discharge might just indicate the body is doing its normal function of clearing the sinus and nasal passages. However, if your baby’s cold lasts longer than 10 to 14 days or has severe symptoms accompanying it, such as lethargy or dehydration, you should take them to the pediatrician for assessment.

Vomiting

If your infant is exclusively breastfed, the best thing you can do for them through a stomach bug that causes vomiting is to continue to try to breastfeed. Breast milk is more easily digestible by babies than electrolyte replacement drinks such as Pedialyte, so breast milk is preferred in any illness with an infant.

If your infant vomits after nursing, try shortening the nursing session to five or 10 minutes and waiting a few hours to see if the baby can keep the feeding down. If your baby is not able to nurse or vomits everything up after 24 hours, you should seek medical attention.

For formula-fed babies, you can offer 0.5 to 1 ounce of oral rehydration solution in a bottle or syringe, such as Pedialyte, every 15 minutes for two or three hours. If vomiting occurs, wait 30 minutes and try again. If your baby is able to keep the solution down, you can resume normal formula feeding.

Fever

If your infant has a fever that rises above 104 degrees repeatedly, you should call their healthcare provider right away. If their fever persists for more than 24 hours, or they are still acting sick after the fever is brought down, you should also call their provider.

Thrush

If your baby has white patches on the inside of their mouth or tongue, or develops a diaper rash that appears symmetrical and will not go away with diaper rash cream treatment, it might be thrush. Your baby's pediatrician can evaluate them for thrush and may provide an oral medicine for the mouth or an antifungal cream for diaper area infections.

Keep a Close Eye

Since your 4-month-old is reaching for objects more often, it's important to keep hot liquids like coffee and tea out of reach. Dr. Segura also cautions you to keep a close eye on them once they start rolling over. "Falls are the most common injury in this age," she says. "Now that babies are starting to roll at 4 months, never leave your baby unattended on any place above floor level, such as the changing table, because falls can happen in less than a couple of seconds."

4-Month-Old Baby Care Basics

Here are some basic care tips for your 4-month-old.

Burping Your Baby

While burping your baby is important, they might not need to burp with every single feeding at this age. As your baby is able to sit up more and hold their head up better, they may be able to tolerate feedings without burpings now. Every baby is different though, so if your little one seems uncomfortable or gassy, continue burping after feedings.

Preventing Bug Bites

Most insect repellents are safe to use on your baby once they are 2 months old. If you and your little one are outside often, exercise caution and do your best to protect your baby naturally by using products with natural ingredients and avoiding buggy areas like under trees or other foliage. Mosquito nets are another option.

Sun Safety

Since babies younger than 6 months old should not wear sunscreen, it's best to avoid direct sunlight. Try staying in the shade whenever possible, and limit sun exposure during the peak daylight hours between 10 a.m. and 4 p.m. If they do have to be exposed to the sun, make sure to dress them in protective clothing, including sun hats.

Avoiding Honey

Babies younger than 12 months-old should never be given honey. This is due to the rare but serious risk of botulism, which can cause abnormal functioning of the nerves, leading to weakness and paralysis.

What Else to Know About Your 4-Month-Old Baby 

Your 4-month-old is quickly growing and changing, so be sure to take plenty of photos! Keep a close eye on developmental concerns, but try not to worry. Your pediatrician is there to guide you every step of the way.

If you're breastfeeding and made it this far, be proud of yourself! Getting through the first few months of nursing can be the hardest. If you have chosen another feeding route for your baby, such as combination feeding or exclusively using formula, pat yourself on the back. Breastfeeding isn't right for everyone, and you should be proud of yourself for going with your gut. Ultimately, fed is best—and both breastmilk and formula offer appropriate nutrition for your baby.

If you're struggling or feeling overwhelmed, remind yourself that it's common and OK to need some help. Raising a little one is no easy feat! Keep up the amazing job. Whether you are a working parent, a stay-at-home parent, or somewhere in between, you should know you are exactly the type of parent your baby needs. At this age, your baby needs routine and reassurance they are loved and cared for and will continue to grow and thrive.

This is often the age that developmental concerns can become apparent. If you are dealing with a difficult diagnosis or news about your baby's physical or cognitive development, search for an in-person or online support group of parents who have gone through the same thing you have. Lean on other parents who can help, offer advice, and give you the support you need.

Most importantly, congratulate yourself on your journey so far! You're moving past the initial newborn stage and your baby is becoming their own little person with an infectious, adorable personality. Enjoy these new milestones!

Frequently Asked Questions

  • What should baby do by 4 months?

    At 4-months-old, your baby is starting to show more of their personality! They are able to recognize familiar faces, respond to affection, smile, and might even laugh. They are able to sit up with support and push up onto their elbows or hands during tummy time. They are able to hold their head more steady and may have also started rolling from tummy to back.

  • Can a 4-month-old baby sit?

    While 4-month-olds are constantly building neck strength, they are still unable to sit up on their own. They are, however, able to sit up with support.

  • Can I give my 4-month-old water?

    Since breastmilk or formula is all your baby needs at 4 months old, the AAP recommends that you do not give your baby water until they are 6 months old.

  • Can I give my 4-month-old baby food?

    Most babies start solid foods between 4 and 6 months old. It's best to speak to your pediatrician about your child's specific needs and whether it is OK to start solid foods.

  • How many naps should a 4-month-old take?

    Your 4-month-old should be taking around four naps per day, totaling an average of three to four hours of daytime sleep.

  • How long should tummy time be at 4 months?

    You can start your baby with shorter tummy time sessions, around five to 20 minutes at a time. Once they get more used to it, experts recommend babies 3 months and older have an hour of tummy time per day.

  • What is a good feeding schedule for a 4-month-old?

    At 4 months old, babies are still breastfed, bottle-fed, or a combination of both. At this age, they usually take in 4 to 6 ounces per feeding every three or four hours.

A Word From Verywell

You've had four amazing months with your baby! It's exciting to see them grow in so many ways. Watching them become more sociable, interactive, and mobile certainly makes up for the exhaustion caused by the 4-month sleep regression.

If you have any worries or concerns about your 4-month-old, always reach out to your child's pediatrician. In the meantime, enjoy those sweet babbles, smiles, giggles, and rolls!

16 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Academy of Pediatrics. Sleep.

  2. Centers for Disease Control and Prevention. Important Milestones: Your Baby By Four Months. Updated August 11, 2021.

  3. American Academy of Pediatrics. Starting solid foods.

  4. American Academy of Pediatrics. How to keep your sleeping baby safe: AAP policy explained.

  5. American Academy of Pediatrics. Baby.

  6. U.S. Centers for Disease Control and Prevention. Milestone moments.

  7. The American Academy of Pediatrics. How to Keep Your Sleeping Baby Safe: AAP Policy Explained.

  8. American Academy of Pediatrics. Caring for your child's cold or flu.

  9. American Academy of Pediatrics. Fever without fear: Information for parents.

  10. U.S. National Library of Medicine. Thrush in newborns.

  11. American Academy of Pediatrics. Why babies spit up.

  12. American Academy of Pediatrics. Choosing an insect repellent for your child.

  13. The American Academy of Pediatrics. Sun Safety and Protection Tips.

  14. The American Academy of Pediatrics. Botulism.

  15. American Academy of Pediatrics. Should I breastfeed or bottlefeed?

  16.  American Academy of Pediatrics. Emotional and social development: 4 to 7 months.

Additional Reading

By Alex Vance
Alex Vance is a freelance writer covering topics ranging from pregnancy and parenting to health and wellness. She is a former news and features writer for Moms.com and Blog Writer for The HOTH. Her motherhood-related pieces have been published on Scary Mommy, Motherhood Understood, and Thought Catalog.

Originally written by
Chaunie Brusie, RN
Chaunie Brusie, RN
Chaunie Brusie is a registered nurse with experience in long-term, critical care, and obstetrical and pediatric nursing.
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