Is there anything that could melt your heart faster than a gummy smile from your 3-month-old baby?

Three months is when you may feel like you are starting to hit your stride as a parent and have become accustomed to living with your newest family member.

You may also find yourself confronting the reality that babies grow and change on a nearly daily basis.

This is the age at which your baby may be smiling and cooing, reminding you how great it is to have a baby.

At 3 months of age, babies are gaining more control of their head, hands, and legs, and you may notice them moving them more deliberately. And while they’re not yet mobile, you still need to keep a close eye on them and make sure to put safety first at all times.

You may be amazed at how quickly your baby grows, but that’s normal. After all, they’re still spending a fair amount of time eating and sleeping.

By now, your baby has probably outgrown their newborn-sized clothes, relegating them to the hand-me-down pile, and put on some irresistible baby fat. You may have already moved on to the 3-month or even the 6-month outfits by now.

What’s typical, size-wise, for a 3-month-old baby? On average, baby boys will be slightly larger than baby girls.

You’re looking at an average of about 24 inches (61.4 cm) in length and just a smidge over 14 pounds (6.37 kg) in weight for a baby boy. Meanwhile, a baby girl in the 50th percentile will be around 23 1/2 inches (60 cm) and weigh about 12 pounds and 12 ounces (5.8 kg).

But of course, your baby may be larger or smaller, and that’s OK. Generally speaking, babies tend to grow between 1/2 inch and 1 inch per month during their first 6 months of life. Plus, they’re gaining 5 to 7 ounces per month. So, if your little baby suddenly looks much bigger, that’s because they probably are!

When your neighbor casually asks how the baby’s doing and puts a little pressure on you by inquiring if your baby has started crawling yet, it’s helpful to be knowledgeable about the developmental milestones for a 3-month-old baby.


Everyone loves to make a baby smile, and in fact, social smiling is a 3-month milestone. So, break out your silly faces and best peekaboo game. Some other social milestones include:

  • having a good time playing with other people
  • crying or protesting the end of playtime
  • imitating your movements and facial expressions
  • becoming more expressive


At 3 months, your baby may:

  • raise their head and chest when lying on their belly
  • open and close their hands
  • hold their upper body up on their arms when on their belly
  • kick their legs when lying down
  • try to bat at objects that are dangling in front of them

This can be a great time to put your baby down on their stomach for a little tummy time to work on these skills. Some babies at this age might flirt with rolling over, so be sure to keep a close eye (and hand) on them.

Other milestones

You may also want to keep an eye out for visual and hearing milestones, such as:

  • following moving objects
  • looking closely at faces
  • recognizing familiar people and objects at a distance
  • vocalizing vowel sounds, also known as cooing
  • turning toward sounds or noises
  • imitating some noises and sounds
  • starting to use their hands and eyes together

If you’re concerned that your baby’s not hitting certain developmental milestones, be sure to ask your child’s doctor.

Like many new parents, you’re probably dreaming about getting more sleep. You may feel like you can’t even remember the last time you got a full night’s sleep.

It might comfort you to know that your baby will eventually sleep through the night. Although, it might take a while longer for your baby to give you this precious gift.

According to the American Academy of Pediatrics (AAP), babies don’t develop regular sleep cycles until they’re about 6 months old. Your baby may sleep 12 to 15 hours a day, but it’s not all in one long stretch.

Many babies between the ages of 3 and 6 months can sleep for 6 to 8 straight hours at night, which experts consider to be “sleeping through the night.” So your 3-month-old baby may start to give you one good long stretch at night, but they may also wake throughout the night.

Don’t give up. As babies get older, they’re able to sleep for longer stretches. When this happens, you’ll be able to log more Zzz’s yourself.

Is there ever an actual “typical day” with a young baby? Maybe not, but there are some things that you can expect, with some variations.

Your baby will wake in the morning, ready to eat. If you’re breastfeeding, you know the drill. If you’re using formula, it’s time to get that bottle ready.

Of course, your baby will want to eat several more times during the day. Three to 4 hours between feedings is pretty common.

How much will they want to eat? At this age, somewhere between 4 and 6 ounces of milk is a pretty average amount for a formula-feeding.

The AAP suggests that babies in this age range consume 2 1/2 ounces of formula for every pound of body weight. So that’s about 30 ounces of formula per day for a 12-pound baby.

Your baby will be more alert when awake, compared with how they were just a few weeks ago, so try reading a few simple books or singing songs and watch for their reactions.

After some playtime, your baby may be ready for a morning nap. Babies at this age tend to take several naps throughout the day.

You’ll also be changing a fair number of diapers throughout a typical day.

Ideally, you want to change your baby’s diaper every time they soil it to reduce the risk of diaper rash. You might change as many as eight or nine diapers per day, although your baby’s needs may vary.

You may wonder what sort of conditions and illnesses you should watch out for. Cradle cap and diaper rash are both pretty common among babies this age, and they’re usually easy to treat.

While you hopefully won’t have to deal with any serious illnesses or health conditions, even healthy babies may catch a cold or cough, especially if they’ve got an older sibling who likes to get up close and play with them.

A runny nose, sneezing, irritability, and even trouble sleeping are common symptoms.

If you’re concerned, be sure to call the pediatrician. Some reasons that might justify a professional opinion include a fever above 100.4°F (38°C), vomiting, trouble breathing, difficulty feeding or waking up to feed, eye discharge, and a decrease in wet diapers.

At 3 months of age, your baby is not yet mobile. That’s coming soon, so you may already want to be thinking ahead to babyproofing your home. In the meantime, be sure to focus on several other important safety issues, including:

  • Safe sleep. Your pediatrician has likely advised you to put your baby to sleep on their back and in their own sleep space, which is safer than sleeping on their stomachs. Read up on the AAP’s sleep policy and make sure you’re following all the guidelines to minimize the risk of sudden infant death syndrome (SIDS).
  • Car safety. Always make sure your child is buckled securely into a rear-facing car seat before taking them in a motor vehicle. Double check all the straps to make sure they’re fastened correctly, and make sure your baby doesn’t slump down in the seat.
  • Choking. You want to keep an eye out on your baby when they’re starting to put things in their mouth. Be sure to move any objects that could pose a choking hazard out of their reach.
  • Falls. Babies wiggle. It’s just what they do. And if you take your eyes and hands off your baby when they’re on a changing table or bed, your baby might just wiggle off of it — and onto the floor. That’s why the AAP urges you to never leave your baby unattended.
  • Burns. Turn down the temperature of the hot water at your home so you don’t accidentally scald your baby during bath time. Keep the temperature no higher than 120°F (48.9°C).

Safety note

Sleep positioners and wedges are not recommended while feeding or sleeping. These padded risers are intended to keep your baby’s head and body in one position, but are not recommended by the Food and Drug Administration due to the risk of SIDS.

Was this helpful?

While 3-month-old babies often have many things in common, the truth is that no two babies are alike. Certain developmental milestones are typical, but not every baby reaches them in exactly the same way.

Some babies sleep better than others, and some babies eat more than others. Your child’s pediatrician can chat with you more about your child’s specific growth and development — and what to keep looking for as your baby continues to grow.