Newborn to Toddler: Growth, Sleep, and Mental Leaps

Your baby is growing by leaps and bounds during his first two years. He goes from a baby who needs help doing everything to a toddler who can talk, walk, and feed himself, among other things. During this time, some important growth spurts and mental leaps happen typically around the 4 month, 9 month, 13 month, 18 month and 24 month mark. (see  Use the chart here to calculate your baby’s exact age in weeks and months and read on to find out what’s going on inside that tiny body!

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Week 1 to Week 4

The first three months of your baby’s life are considered the fourth trimester, as he’s still developing. During weeks 1-4 you should basically be feeding your baby on demand. The frequency really depends on your baby since all babies are different. During this first month, your baby will undergo growth spurts at:

  • 7 to 10 days
  • 2 to 3 weeks
  • 4 to 6 weeks
Baby, Growth, Parenting
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Wonder Week 5; Mental Leap 1

Changing sensations

You have watched your baby grow rapidly over the past 4 weeks, and you’re starting to feel confident that you know all of his little ways. That’s just about the time he’s ready to take his first development leap to throw you off!

During this time, your baby is starting to feel new sensations other than just hunger and discomfort. Your baby is experiencing everything for the first time! Besides all of the mental action, his internal organs are also developing at the same time.

6 to 7 weeks

Between 4 to 6 weeks of age, your baby will be going through a growth spurt.Baby, Growth, Parenting

Wonder Week 8, Mental Leap 2


Get ready for patterns at about 8 weeks of age. Your baby will not only notice what’s going on around him, but also what’s going on inside him. These are signs that mental changes are happening.
Baby may spend hours playing with his hands and feet and trying to control them or trying to listen to himself by making short bursts of sound. The newborn may also become fascinated with shadows or start to study the details of everything around him.

9 Weeks or 2 Months Old to 11 Weeks

This is still the fourth trimester. Don’t watch the clock! Your baby is getting used to new abilities and is learning more each day.

Baby, Growth, Parenting
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Wonder Week 12, Mental Leap 3


At this point your baby starts to become aware of other senses and notices how the world around him changes. Things life a shifting voice, dimming lights or a setting sun all become noticed. You may notice physical movement more than the mental changes that are happening during this time.

Week 13 or 3 Months to Week 18

Your baby will undergo two growth spurts during this time; one at 3 months old and another at 4 months old. Don’t be surprised if sleep gets messed up during this time! It has nothing to do with the way you’re parenting; it’s just a sign of the times.

Baby, Growth, Parenting

A note on sleep regression

This is a good time to talk about sleep regression. Developmental milestones are not just physical, but also emotional and neurological.

Babies process information in their sleep. This means they will babble, try to crawl, move their feet and perform all the new skills they are learning in their sleep. They probably rolled over in their dreams and then did it in reality, which woke them up.

Basically, their busy brain is not letting their body get as much sleep as they would like. That’s why they’re so fussy and clingy during these developmental milestones. As they master each milestone, their sleep pattern returns to normal…that is until the next milestone hits!

You just have to ride the wave!

Wonder Week 19, Mental Leap 4


For your baby everthing is new…EVERYTHING!

When someone drops a rubber ball on the floor, you know it will bounce back up and continue to do so a few times. If someone jumps up, you know they will come back down. You know what follows; your baby is just learning all of these things.

During the previous mental leaps, your baby was able to see patterns and notice transitions, not only visually but also in sound, smell, texture, and movement. Now, your baby can understand the world better as he starts to experiment with events.

20 Weeks to 24 Weeks

Your newborn is acquiring new skills and learning towards becoming a toddler.

Baby, Growth, Parenting
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Wonder Week 26, Mental Leap 5


At 26 weeks, your baby should start to show signs of another mental leap by making connections and understanding relationships of the world.
The most significant of these is distance. The world is suddenly much bigger. Consider the fact that babies are limited to get to places, so anything further than arm’s length can be terrifying! If you go into the next room, you may as well be in China as far as your newborn infant is concerned.

28 Weeks to 36 Weeks

During this time, your baby may also have another growth spurt. So, don’t be surprised if he wakes up more frequently during the night.

Baby, Growth, Parenting

Wonder Week 37, Mental Leap 6


After 37 weeks, you will start to notice that your baby becomes very methodical. The newborn picks up tiny specs off the floor and studies them and tries to taste them. Your baby may also rearrange food and touch it to feel the texture, or squish a banana just to feel it pass through his fingers. While you may be less than thrilled about his mess, know it’s all part of the game! Your baby is doing research and categorizing everything from smells, to animals, to people.

40 Weeks, 9 Months

Growth spurt alert! You know what this means…more wacky sleep patterns.

Baby, Growth, Parenting
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Wonder Week 46 Mental Leap 7


During the last mental leap your baby was destroying everything, at the 46 week mark you may notice he starts putting things back together. Hurray! It all has to do with sequences. The newborn starts to learn that things go in a certain order.

Week 48

Alert! Baby will wake up more frequently at night!

Week 52 or 12 Months Old

Your baby may still be experiencing some sleep issues, remember it’s not you and it will pass!

Baby, Growth, Parenting

Wonder Week 55, Mental Leap 8


The end of the first year is a biggie because it means your baby is about to become a toddler! Shortly after your baby’s first birthday, he will be ready to experience the world of programs. This means learning that “if this happens, then that will follow”. This is key as the toddler learns decision making.
Want to know what happens in the second year? Check back next week.

Has this post helped you to better understand your baby’s behavior?  Please share in the comments section.

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