3 Month Baby – Milestones and Development

Congratulations, Mom and Dad! This month marks the first month your baby is past her newborn stage. What a milestone that is! Give yourselves a pat on the back because it has not been an easy transition.

I’m sure you have noticed that your baby looks and behaves quite differently than she did when she was a newborn. That’s because your baby has gone through a whole 12 weeks of constant developmental changes. This month will bring new challenges and changes of its own.

This article is a continuation of the Baby’s first year series.

Previous article: 2 month old baby development


3 Month old Baby Development

Even though your baby has been able to recognize you since just a few days after birth, she may now begin to show it. You will start to see the obvious preferences she has towards you, your partner, and a select few others who have been consistently present in her life as compared to those who may “ooo” and “aah” at your baby on occasion. She will start to scan the room to find you and when she spots you, she may start to show physical signs of excitement like smiles or waving her arms.

Take it all in, mom and dad.

What else does this mean? Your 3 month baby is taking note of the world around her. This is a big leap in her development.

Right now, your baby should begin raising her head and chest while on her stomach with support from her arms, kicking her legs while on her stomach or her back. You will see her making a grasping motion with her hands and bringing them to her mouth, pushing down with her feet when they are placed on a flat surface, attempting to grab dangling toys and other objects, and grasping and shaking hand toys.



Social Interaction

Your baby should also be able to watch faces, follow moving objects, recognize familiar objects and people in the distance, start developing hand-eye coordination, smile at the sound of mom or dad’s voice, babble, imitate certain sounds, and follow sounds with her head.

At 3 months old, your baby should have a “social smile,” enjoy playing with other people and even cry when playtime ends, start communicating and expressing emotions with her face and body, and imitate some movements and facial expressions she has seen from others.

If your baby struggles with any of these things, make sure to keep an eye on it. If you feel that your baby isn’t where she should be developmentally, you can always ask your doctor.


Baby Weight

According to the World Health Organization, your 3 month baby weight should be between 13.0 – 15.2 pounds (for a boy) or between 11.8 – 14.0 pounds (for a girl). Now, this doesn’t mean that if your baby doesn’t fall into those categories that you’re doing something wrong or your baby is unhealthy. These estimations are taken from the 25th to the 75th percentiles, meaning that half of all 3 month old babies fall into these categories. If your baby seems to be gaining weight at a regular rate, you shouldn’t be too concerned.

At next month’s appointment with the Pediatrician, your baby’s doctor will weigh and measure her. Based on the results, they will let you know exactly what (if anything) needs to happen so your baby maintains her good health. If you still have concerns about her growth, talk with your doctor.

As a side note, babies who are born prematurely should use their gestational age in determining their weight estimations, not their age since birth.


3 Month Baby Sleep

You may begin to notice that your baby is starting to regulate her sleep schedule. This means longer stretches of sleeping, with bouts of feedings in between. This also means more time awake during the day. Don’t worry if that’s not the case though. It may take a while longer for your 3 month baby to adjust.

With more wakefulness during the day and less interrupted sleep at night comes more regular feedings throughout the daytime versus nighttime.

An example of a sleeping and breastfeeding schedule for a 3 month old might look something like this:


7:30a – Wake*

8:00a – Feed

9:00a – Nap*

9:30a – Wake/Feed

11:30a – Feed/Nap

1:30p – Wake/Feed

2:30p – Nap

3:00p – Wake/Feed

5:00p – Feed/Nap

7:00p – Feed

7:30p – Catnap

9:30p – Feed/Bedtime*

11:00p – Fill-up Feed (This should take place at Mom’s bedtime, giving mom a longer stretch of sleep)


This schedule may also include 1-3 additional night feedings.

* – These should be set times in your baby’s wake/feed schedule, giving your baby the opportunity to start to adopt a schedule as she grows older.

A formula-fed baby differs from this schedule only in that formula keeps babies fuller for longer than breastmilk, so they are more likely to have less feedings throughout the day than a breastfed baby and may nap a little longer than a breastfed baby.

You are welcome to use this schedule as a guideline, but be aware that it may not work with what your baby, or her body, have in mind. Just be patient and you will start to find a schedule that works for everyone.


Baby Poop

Yup, we’re going there.

Since month 2, your baby has transitioned from about 10 poopy diapers to just 2-4 per day, assuming she is exclusively breastfed. This is because as your baby grows, her gastrocolic reflex matures and her intestines absorb more from the milk she eats. This creates less waste, and, therefore, there is far less of a need for her body to make room for more food through the act of pooping.

Formula-fed babies poop even less than 2-4 times per day. This is because the formula moves much slower through the intestines. This amounts to 1-2 poopy diapers every 1-2 days. Babies who are both breastfed and formula-fed can poop anywhere from multiple times a day to once per week.

Breastfed 3 month old baby poop has a range of colors depending on mom’s diet, though it is most often yellow. It is usually seedy or curdy, so if it looks like it can roll, your baby is probably constipated. Breastfed baby poop at this age should be odorless.

Formula-fed 3 month old baby poop should have pretty consistent coloring, but if you see variations throughout the week, don’t panic, that’s normal. It resembles pudding in consistency, so, just like breastfed baby poop, it also shouldn’t be able to roll. There is a slight odor to formula-fed baby poop, usually due to the formula taking longer to digest, and, therefore, spending more time in the intestines than breastmilk. The longer poop sits in the intestines, the smellier it becomes.

So when do you call the doctor?

  • If her poop is white, black, or red
  • If she yells from pain or bleeds while pooping
  • If mucus is present in the stool, which could indicate infection or an intolerance
  • If, after introducing a new food through breastmilk, her stool changes dramatically
  • If she has diarrhea more than 5 times per day.

Antibiotics, stomach viruses and traveling can all affect your babies stool. But if you are unsure, it’s best to call the doctor.


Anna C

Anna is the main author of this website. Like many of you, she is a mother who is continuously searching for the best parenting tips in order to learn more about child development.