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YOUR 3-MONTH-OLD BABY’S DEVELOPMENT

3-month old baby development
Dr Simon Carvell
Medically reviewed by
19th Dec 2023

Once your baby hits the three-month mark, you will have noticed many changes in them. Right now, you may find yourself in more of a routine with your little one, and your life before parenthood may now seem like a distant memory.

If you are not in a routine yet, don’t worry, every baby is different, and you will get there soon enough. Here’s what to expect once your baby reaches three months:

Baby’s Growth and Overall Health at 3 Months

When your baby reaches three months old, they will probably have moved up to the next size of clothing and may need to size up in nappies too.

At 12 weeks old, a baby boy will weigh anywhere between 4.5kg and 8kg and measure 55cm to 66cm in length. A 12-week-old baby girl will typically weigh between 4kg and 8kg and measure 54cm to 65cm in length.

Don’t forget that every baby is different, so if you have any concerns about your baby’s weight or length, you may wish to discuss these with your health visitor.

Immunisations

It is now time for your baby to have their second set of immunisations. At 12 weeks old, your baby will receive their second dose of the 6-in-1 vaccines, which protects them against diphtheria, hepatitis B, Hib (Haemophilus influenzae type B), polio, tetanus, and whooping cough, and is given in one injection.

Now is also the time your baby will receive the second dose of the Rotavirus vaccine. In addition, your baby will also be vaccinated against Pneumococcal (PCV) at 12 weeks.

Baby’s Sleep at 3 Months

When it comes to sleep patterns, all babies are different. But on average, your baby will need 14 to 16 hours of sleep every day, with approximately three of these hours spent napping during the day.

At three months old, your baby may now be sleeping for longer stretches during the night and spend more time awake in the daytime. Your baby may sleep for up to five hours at a time during the night. But don’t worry if your little one is waking up more frequently. This could be because they still need frequent feeds through the night to sustain their growth.

Baby’s Food and Feeding Schedule at 3 Months

Milk is the only food your baby needs throughout their first six months. At three months old, your little one may be having five to eight feeds across each day.

You may notice that your baby seems hungrier than usual right now, and this is totally normal. At three months old, your baby may be experiencing a growth spurt, which is why they may feed more.

Vitamin D

It is recommended that babies that are exclusively breastfed take a daily vitamin D supplement through their first months. Your health visitor will be able to advise you on the best supplement for your baby.

Baby’s Personality at 3 Months

At 12 weeks old, your baby will now seem a lot more active, and changing their nappy will likely be a much more lively experience.

Babies of this age often wiggle and kick their legs a lot, so it is crucial to take care when changing and dressing your baby. As your baby will now be wriggling and rocking lots, you may wish to put them in their cot to sleep now rather than in a Moses basket on a stand.

As well as being wiggly, your baby will now be super giggly and smiley. This makes the three-month stage a magical time, and you will probably spend a lot of your time trying to make them smile.

Baby’s Milestones at 3 Months:

  • Your baby will be able to hold a simple toy in their hand.
  • At 12 weeks old, your baby will giggle out loud and smile lots.
  • Three-month-old babies move their heads in the direction of sound when they hear a noise.
  • Your baby will be fascinated by their hands and examine them closely.
  • Your baby will be able to lift their head and shoulders up for a few moments during tummy time.
  • Your baby may pick up objects and bring to their mouth.
  • Three-month-old babies also have the ability to mimic sounds.
  • Your baby may be able to roll onto their front

Games and Activities for Baby at 3 Months

At three months, your baby will be starting to interact more, and this means you can have lots of fun together. Here are some games and activities you can try with your three-month-old baby:

Play with Age-Appropriate Toys

Small age-appropriate toys, such as rattles, are excellent for playtime at this age, as your baby will be able to hold them and wave them around. Three-month-old babies also enjoy using play mats and activity gyms and especially love batting at the hanging toys on these with their hands. This is an excellent way to develop hand-eye coordination.

Read to Your Baby

This is a great age to introduce books to your little one. Showing your baby chunky board books or cloth baby books is an excellent addition to your daily routine. Your baby will be delighted by the colourful images and different textures of the books.

Play Games

Have fun with your little one by playing peek-a-boo, tickling their tummy, and chatting with your baby. As well as being a great bonding experience, you will also be rewarded with plenty of giggles.

How mum's feeling at 3 months postpartum

 

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Mum's View

"For me, with my third baby, the fourth trimester was a happy bubble full of excitement. Everything was wonderful and straightforward. Just as I hoped!

The exhaustion and sleepless nights were real, but I was well-equipped and prepared to deal with them by now… I knew what to expect and what was coming, after experiencing it twice before.

However, with my firstborn I had a totally different experience.

It was all new to me.

The fourth trimester was one where I needed more support than I initially realised I would.."

 

Mum of 4, Harriet

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Mum's View

"When Jack was first born I felt so jealous of my previous life and the freedoms I had.

I wanted to be with my baby and bond but I desperately wanted to see the old me in the mirror. Being at home and cuddling was lovely and exactly where my heart lived but I would have given anything to jump in a time machine and be a teenager riding my bike around my neighborhood with my little sister.

My mothering instinct was kicking in by the day and all I wanted to do was be with my baby, cuddle him all day long and look after him - I also, fleetingly, wanted to run for the hills."

 

Mum of 1, Rosie

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Mum's View

"You know you’re a parent to a newborn when…

Your camera roll is full of nearly the same picture.

Your new baby is adorable, and you want to capture every sweet moment of your baby’s life, so you take dozens (maybe even hundreds) of photos every day, especially of your baby when they’re sleeping peacefully. It doesn’t matter that nearly all photos look the same, these are precious moments for you."

 

Mum of 3, Petra

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