3 Month Old Baby: Milestones & Development

Team Peanut10 months ago7 min read

Wait a minute. 3 months? How on earth did that happen? It’s now been roughly a year since you discovered your world was about to change - and oh boy has it changed!

3 month old baby

The 3 month mark signals the end of what experts like to call the fourth trimester. Those first 12 weeks on the planet involve a heckuva lot of growth and development, and it all culminates in the fact that your baby’s now no longer considered a “newborn.”

That’s right. We’re officially in infant territory, mama.

3 month old baby developm ent

Infants tend to stay awake for longer periods during the day and, fingers crossed, sleep for longer through the night. You’ll also start to notice more smiles, more personality, and more head control as your baby continues to blossom. Meanwhile, they’re Hulking out of their sleepsuits and you’re wondering if anything fits…

And that’s just the tip of the iceberg where milestones are concerned.

Exciting 3 month old milestones

When you’re with your baby all day, every day, it can sometimes be tricky to spot the small changes as they grow and develop. But month 3 brings with it a few hard-to-miss moments, so keep your camera within reach:

1. Baby’s on a roll. It’s around now that tummy time starts to pay dividends. Those mini-planks progress into full-on rolls, and eventually your baby will land face up. Stick with tummy time to strengthen those muscles. And don’t worry about them not rolling back onto their front straight away; this can be harder to master and will take a little longer.

2. “Ouch, that’s mama’s hair!” Your baby’s eyesight is improving all the time, to the point that now they’re able to track movement from greater distances. They’re also developing a smidgen of hand-eye coordination. Just enough to grab for something colorful, or take a fistful of your luscious locks.

3. Sitting, standing (with support). With a helping hand or two, your baby should be able to sit up on your lap and hold their head reasonably steady. And as they continue to adjust to life outside the womb, they may also be able to bear weight on their legs, if you hold them upright in a standin” position, that is.

4. A world of sights, smells, sounds, and textures. You may take this for granted but look around you. There’s a lot to see, smell, hear, and feel — and your baby’s really starting to appreciate that. They don’t yet have depth perception, but they can recognize objects, turn towards loud noises, respond to your unique scent, and actively enjoy different textures. The fun and games are (quite literally) about to begin.

How much does a 3 month old baby eat?

All of this development requires fuel, so how much should your 3 month old baby eat?

At this point, your baby’s stomach has naturally grown in size, so they should be able to go longer between meals. Whether you’re still breastfeeding (around half of mamas are at this point), mixing boob and bottle, or you’re using formula, you’ll probably find that your baby will take in around five ounces between six and eight times a day.

Of course, this will vary from one little one to another, and you need to do what’s right for you and your baby. Trust yourself that you know the difference between when your baby’s hungry or just fussy, and if you have any concerns, don’t be afraid to ask for help on Peanut.

What is the normal weight for a 3-month-old baby?

Forget “normal” for a second. The average weight of a 3-month-old baby is 5.4kg (12lbs) for girls and 6kg (13.2lbs) for boys — but remember, this is just an average.

For a more accurate take, check your baby’s weight in relation to their length on a height-weight chart:

  • If both height and weight are on a similar curve, then all should be okay. They might be a bit bigger or smaller than the average, but rest assured, they’re on the right track.
  • However, if weight is outpacing height (or vice-versa), speak to your pediatrician or healthcare provider. This could be a sign that your baby is gaining weight too quickly (or not fast enough).

How do I keep my 3 month old entertained?

At month 3, your baby has discovered that there’s more to life than eating, sleeping, and pooping — although those activities will still take up a healthy chunk of their day.

So, now you need to incorporate some entertainment into the mix. Don’t worry, you won’t need to learn how to juggle, and a unicycle is, almost certainly, overkill.

Instead, fall back on the oldies but goodies: songs, toys, and stories.

  • Books with different textures or sounds built-in will always go down a treat at this stage. You could also try using different voices, tones, and noises as you read.
  • Classic nursery rhymes and songs will elicit smiles and giggles (from you both). Try and incorporate your baby’s name so they get used to hearing it.
  • Bright, colorful, squeaky, or rattly toys will be popular too, as your baby starts to grasp, examine, and explore.

How much should a 3 month old sleep?

If you’re lucky, this is the point where your baby starts to sleep through (most of) the night. For an infant, this is typically seven to nine hours of uninterrupted snoozing.

However, you should bear in mind that if your baby falls asleep at 7pm or 8pm, this stretch of slumber will take them up to around 2 am or 3 am. Still, that’s better than being woken several times throughout the night!

Your baby will also partake in a few daytime naps to top up their beauty sleep (usually between two and four, totaling four hours).

To avoid your baby becoming overtired and therefore less likely to sleep through the night, keep your eyes peeled for signs that they’re ready for bed. If they’re fussier than usual, wanting to nurse or take a bottle when they’re clearly not hungry, or rubbing their eyes, it’s probably time for their jammies.

In terms of safe sleeping practices for a 3-month-old, your baby should still be sleeping in the same room as you to reduce the risk of sudden infant death syndrome (SIDS), and if they’ve shown signs of rolling over, you should stop swaddling them.

The bottom line when it comes to sleep is to try and stick to a consistent routine. Keep bedtime and nap times the same, day in, day out, and you’ll both reap the benefits!

Does this get easier?

You’ve almost certainly uttered that question throughout the first 12 weeks of being a mama, and at 3 months in, you now have an answer: Sort of!

It’s not that being a mama is any easier; it’s that you’re better at it now. You can spot signs of hunger and tiredness, you know your way around a dirty diaper, and you can feed with your eyes shut.

When you combine those finely honed skills with your baby settling into something resembling a routine, everything becomes that little bit more predictable.

Of course, life with a baby will throw you quite a few curveballs going forward, but don’t worry — you’ve got this! And remember, if you ever need advice or an answer, even in the small hours, the mamas on Peanut have got your back.

Read also: Baby Teething at Three Months? What to Know

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