Your 4-month-old baby's growth and development (2024)

It's official – you're no longer the parent of a newborn. (Is someone chopping onions in here?) Your baby is officially an infant, leaving the free-for-all newborn days behind.

Read on for the exciting developments in store this month – and if you'd like more information onphysical milestones, including expected timelines and fun play ideas to help your baby hit their milestones, check out Meeting Physical Milestones Through PlayOpens a new window, a premium offeringfrom BabyCenter Courses.

Your baby's development

Get ready to see some major strides in your baby's social and emotional development this month. A lot of crucial brain development happens around the 4-month-old mark, and you'll see this reflected in how your baby can increasingly recognize important people, express happiness and sadness, and communicate moods and desires.

4-month-old milestones

Here are some of the milestones that your 4-month-old baby may reach:

• Smiling. Those days of guessing whether it's gas or a real smile are over. Your 4-month-old may be treating you to tons of gummy grins, and your baby will especially love to smile at familiar faces.
• Recognizing familiar objects. Along with recognizing your face (your baby's favorite), your 4-month-old will also start recognizing familiar objects. Encourage this skill by pointing things out in your environment, like your dog or a favorite blanket.
• Playing with toys. This is the start of many long, long years of tripping over toys on the floor. It's worth it: A baby playing is actually hard at work making new connections in their brain and mastering gross and fine motor skills. Check out these great developmental toys for your 4-month-old.
• Getting frustrated when playing stops. Now that your baby has discovered what playtime is, they may show frustration or even cry when it's time to stop. This is actually a social and emotional milestone to celebrate!
• Working on language. Your baby may imitate the sounds you make and even your facial expressions. To encourage language development, talk to your 4-month-old whenever you can, narrating your daily excursions and activities around the house.
• Hand-eye coordination. Your baby's hand-eye coordination is on point this month. They may be able to spot an object they want and then reach for it in response, all in one coordinated movement.
• Reaching and grabbing. All that advanced hand-eye coordination means that your baby will most likely be reaching and grabbing for anything interesting that catches their eye – including your hair, earrings, necklace, or coffee cup. Watch out!
• Holding their head steady. If they're not already, soon your baby will be able to hold their head up steadily without any support. This one is huge! There's a whole new world around them, just waiting to be seen. Head control is the foundation of many future physical developments, including sitting up and walking.
• Rolling over. Many babies will start to roll over from their stomach to their back this month, or at least get halfway there. Be sure to keep an eye out for this particular skill, as it means it's time to stop swaddling your baby and using a bassinet. Also, be extra careful to keep one hand on your baby if you change diapers on an elevated surface, like a changing table or a bed.
• Pushing up on elbows. During tummy time, your 4-month-old will likely be able to push up onto their elbows and support the weight of their head and chest. This is commonly called a "mini push-up," and if you do yoga, you'll recognize it as cobra pose!

Although babies follow fairly predictable patterns of development, all babies are different. It's a good idea to be aware of milestones and tell your baby's care provider if you have any concerns about developmental delay. But keep in mind that some babies just need a bit more time to learn skills and hit milestones.

4-month-old weight and length

How much should a 4-month-old weigh? By this age, most babies have doubled their birth weight. That means that if your baby was born at around 7 pounds, chances are they weigh in around 14 pounds now. Pat yourself on the back for all of those round-the-clock feedings – they worked!

Here are the average weight and lengths for baby girls and boys:

Baby girls

Average weight for a 4-month-old: 14 pounds 2 ounces
Average length for a 4-month-old: 24 1/2 inches

Baby boys

Average weight for a 4-month-old: 15 pounds 7 ounces
Average length for a 4-month-old: 25 1/4 inches

Keep in mind that these numbers are all averages and it's perfectly normal if your baby weighs or measures more or less. Your baby's healthcare provider will ensure that your baby is growing correctly by plotting their measurements on an individual growth chart at every checkup.

4-month-old feeding

This month you may notice a big shift in your baby's eating patterns. Your baby is physically larger and can hold more food in their stomach. The intense growth of the newborn months has slowed too, meaning your baby may go longer between bottles or breastfeeding sessions and eat slightly more at each feeding.

At 4 months old, both bottle-fed and breastfed babies may be able to go 4 to 5 hours between feedings. Bottle-fed babies will have about 4 to 6 ounces of formula or breast milk at each feeding. Your baby may still wake up for nighttime feedings, but it's okay if they don't. You don't have to wake your baby to eat, unless your baby's healthcare provider has advised you otherwise.

The tricky part about 4-month-old feedings is that while your baby will naturally gravitate toward fewer, larger feedings, it's still important to follow your baby's hunger cues, especially if you're nursing. Sometimes, babies need to nurse for comfort, because they're not feeling well, or to fuel a growth spurt.

Wondering when babies can eat solid food? Babies are typically ready to start solids between 4 and 6 months old, as long as they're showing signs of readiness. These signs include:

• Being able to sit upright in a high chair or infant feeding seat
• Having good head control
• Being able to move food to the back of their mouth and swallow it (rather than pushing it back out with their tongue)
• Opening their mouth when food is offered

If you're exclusively breastfeeding, the American Academy of Pediatrics (AAP) recommendsOpens a new window waiting until your baby is about 6 months old introduce solids because exclusively breastfeeding your child is so beneficial. If you have questions about when to introduce solids, be sure to talk to your child's healthcare provider.

After your baby starts solids, breast milk and formula will still provide the majority of your baby's calories and nutrition until they are 1 year old. The AAP recommendsOpens a new window breastfeeding your baby until they are at least 12 months – and longer if you and your baby want to.

4-month-old sleep

There's good news and bad news this month. The good news is that by 4 months old, many babies begin sleeping in longer stretches and may even sleep through the night. (For a baby, sleeping through the night means 6 to 8 hours straight.)

The bad news is that 4 months is also the age for a potential sleep regression. Sleep regressions tend to occur at milestones ages for your baby – when they're undergoing a lot of growth and development. Not all babies go through sleep regression, but parents commonly report problems with their child's sleep patterns at 4 months, 6 months, 8 months, and 1 year old.

So how much should a 4-month-old sleep? The answer varies a bit – some sources say your 4-month-old needs between 12 and 15 hours of sleep (including nighttime sleep and naps) every 24 hours. Other sources put that number at 12 to 16 hours per day, or at 14 to 15 hours a day (about 10 hours at night and 4 hours as daytime naps).

As you can see from those numbers, it's a pretty wide range. That means, of course, that some babies will sleep more than others. If you're one of those lucky parents who has a good sleeper, enjoy it!

If you're not, don't despair. Your baby is still young and you can help develop healthy sleep habits with steps like establishing a bedtime routine and following a sleep schedule that incorporates regular nap times. (Remember, when it comes to babies, sleep begets sleep.)

Here are some other important things to know about sleep for your 4-month-old:

• Nap times. Around 4 months old, your baby will most likely need two to three naps per day. Some babies may take one in the morning and one in the afternoon, with an early bedtime. Other babies may also take a late afternoon nap and have a later bedtime. Naps at 4 months old are typically 1 to 2 hours long. Your baby may be able to go anywhere from 2 to 4 hours between naps, but every baby is different, so follow your baby's sleep cues.
• Sleep training. You can start to sleep train your baby this month if you want to. Sleep training isn't something all parents do, but it can help everyone get more precious shut-eye. And at this point, many parents are exhausted by months of nighttime wake-ups and feel ready to encourage their baby to sleep through the night. There are various sleep training approaches that you can try, so choose the method that you're most comfortable with.
• Sleep regressions. If your baby's sleep gets worse this month, know that it's normal. It's a sign that your baby is growing and developing, and that's actually a good thing – although it won't feel that way at 2 a.m. Sleep regressions can be a challenge, but they're temporary. Stick to your bedtime and nap time routines, follow your baby's sleep cues, and if you feel like you need to, consider sleep training.

Your baby's health

At 4 months old, your baby is due for their next well-baby visit. Regular doctor visits are important to ensure that your little one is growing well. The 4-month visit is also a chance for you to discuss any concerns you have and address any challenges in your baby's sleep or feeding. Here's what you can expect at the 4-month checkup:

• A medical assistant or nurse will take all of your baby's physical measurements, including weight, length, and head circumference. Those measurements will be plotted on a growth chart to track your baby's growth over time. Remember, no two babies develop the same way.
• Your baby's healthcare provider will address any concerns about sleeping, feeding, and behavior and ask about your baby's sleeping and eating habits. They'll also review developmental milestones and check that your baby is developing appropriately.
• The provider will do a complete physical and check your baby from head to toe, including the diaper area.
• The provider will ensure that you're following recommended steps to keep your baby healthy, including giving your baby vitamin D drops, babyproofing your home, using a car seat safely, and practicing safe sleep habits.

Your baby will also be eligible for several vaccines at the 4-month visit. Be sure to ask your baby's healthcare provider any questions you have about the vaccines. It's normal to have questions, and a good provider will help explain the safety and importance of vaccines for your little one.

Here are the vaccines your 4-month-old may receive:

• Pneumococcal vaccine. This shot protects against pneumococcal infections, such as meningitis and pneumonia, which can occur in children younger than 5.
• DTaP vaccine. The DTaP vaccine protects against diphtheria, tetanus, and pertussis (whooping cough). Whooping cough can be especially dangerous in babies, so make sure your baby's vaccination is up to date.
• Hib vaccine. The Hib vaccine protects against a certain type of bacterial infection that can cause serious illnesses in babies, such as meningitis and pneumonia.
• Polio vaccine. Thanks to this vaccine, polio is almost eradicated in the U.S. Prior to widespread immunization, polio – which is caused by a virus – caused paralysis in about 1 percent of people.
• Rotavirus vaccine. Rotavirus is the leading cause of diarrhea in babies worldwide. Diarrhea in a baby is a miserable experience you'll want to avoid if you can. Plus, this vaccine is given orally, so no pokes necessary.
• Respiratory syncytial virus (RSV) shot. RSV is a common respiratory virus that can lead to bronchiolitis and pneumonia. Your healthcare provider may recommend this shot during RSV season (October through May) to help protect your baby.

Your 4-month-old baby: Week by week

Want to learn more about what's happening with your baby this month? Get more details on your 4-month-old's weekly development:

• Your 4-month-old: Week 1
• Your 4-month-old: Week 2
• Your 4-month-old: Week 3
• Your 4-month-old: Week 4