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The 10 Baby Leaps: The Wonder Weeks Of Child Development

The 10 Baby Leaps: The Wonder Weeks Of Child Development

There are these periods of a child’s life where he gets very cranky and tends to cry often. He also tends to cling to his mother a lot more and refuses to let go. These are so-called baby leaps. But what happens during these leaps?

Well, baby leaps signify significant developmental changes in your child’s mental state. These 10 periods are when his mind becomes highly active and undergoes a large shift.

As previously mentioned, this will stir him somewhat and make him a lot crankier, even opening his appetites up.

It’s important to loosen up any rules during these 10 developmental leaps as babies generally aren’t easy to manage during their fussy growth spurt weeks.

When Are The Wonder Weeks?

Luckily, these periods of the baby’s mental development are described in detail in the Wonder Weeks book written by Frans X, Hetty van de Rijt, and Frans Plooij – three wonderful people who give us clarity on these previously unexplained periods of fussiness, crankiness, and clinginess.

The baby leaps that we’re talking usually occur as follows:

  • The first leap – Week 5
  • The second leap – Week 8
  • The third leap – Week 12
  • The fourth leap – Week 19
  • The fifth leap – Week 26
  • The sixth leap – Week 37
  • The seventh leap – Week 46
  • The eighth leap – Week 55
  • The ninth leap – Week 64
  • The final leap – Week 75

These periods are fairly easy to predict and are similar in almost all babies – some may get their leaps a few days or a week earlier or later, but that’s a rare occurrence.

Said periods can also last from anywhere from a day or two to a full-blown couple of weeks, which can be quite a challenge to overcome for new parents.

I know it was rather hard for me during my first time with my first baby because I had no clue why she was constantly crying in these periods and why she was so clingy as to not even want to go over to her father.

It even affected my baby’s sleep and I had immediately thought something was terribly wrong.

Luckily my daughter’s pediatrician calmed the situation down and told me about these leaps that occur in a child’s development and the stages, allowing me to keep track of these fussy phases in the future.

When I had my little boy, I even utilized the Wonder Weeks App to help me keep better track of when one of these developmental milestones was arriving, helping me better cope with the whole ordeal.

And today, I’ve decided to share this knowledge with you so you don’t have to find out about it too late and so you can stop worrying that something is wrong. It’s not – it’s only natural, mammas!

The 10 Baby Leaps

The first leap – Week 5 – A muddled perspective

A portrait of a five week old newborn baby girl wearing a pink bonnet and lying in a basket

In the first few weeks since birth, your baby’s senses are somewhat dulled as is the rest of his body.

He’s going to be rather calm and base his existence strictly on feeding and sleeping as his body develops.

And these developments happen rather quickly, as babies’ physiques change drastically in the first two years of their lives.

Somewhere around the fifth week is when the first leap occurs and the baby’s senses start to sharpen and become more sensitive – his whole world changes as he gets pelted with all of the new information from the outside world all at once. It can get rather overwhelming, especially for an infant.

This is the main reason why he gets quite cranky during this time and should be taken into consideration.

This period is the first time the baby gets to differentiate between life inside the womb and the life outside of it, and is the first step toward growing up.

The second leap – Week 8 – Everything is interesting

Cute newborn baby girl lying in the bed on white blanket with pink teddy

The second leap occurs very close to the first, and is one where the baby has learned to adjust to his newfound senses.

Everything starts to fascinate him and he looks at it in awe, whether it’s the flashing lights of his new toys, the colorful brand logos of your groceries, or the various sounds of the city, nature, and even himself.

RELATED: Why Do Babies Stare? Seeing The World Through A Baby’s Eyes

Your baby will even start becoming more physically active, toppling over various toys and objects like a cat would and flailing his limbs about just to get a hang of them.

These are all things that will occupy infants’ young minds during this period.

This time in baby development is one where they carry an extreme amount of focus and devote it to practicing a single one of these senses.

Trying to interfere with these activities can make babies quite combative and fussy.

The third leap – Week 12 – Sharpening the senses

Laughing baby looking at mom and playing with her

Yet another rather close leap in these 10 infant development leaps, and a rather significant one at that.

This one will primarily focus on the baby’s brain getting a better grasp on his newfound skills.

His eyesight gets more focused and object permanence starts becoming an actual thing, instead of always wondering where his favorite toy disappeared to when you placed it behind your back.

His hearing gets more acute as he starts discerning specific sounds in all the noise.

And, most importantly, his flailing movements become less random and a lot more uniform – your little one is grasping the basics of his gross motor skills.

During this particular baby leap, you might notice your baby gets frustrated as he tries to make sense of all his new skills and fail the first few times, like trying to get a hang of rolling over.

We all do that even when we’re adults – yet respond to it differently (usually) – but an infant has no other means of communicating this other than bouts of crying or the odd tantrum when things get really tough.

The fourth leap – Week 19 – Eventful experiences

Mother and her little baby in towel after bath in room

Here’s where the baby leaps start becoming more spaced out, but start becoming a lot more significant in perfecting your baby’s currently rather crude and basic understanding of the outside world.

This is a period where your little one is going to start experiencing specific events.

While his third developmental milestone had his senses become sharp enough to start noticing the subtleties of every sensation, anything a bit more complicated than that still escaped him.

His understanding of the world is still new and unpredictable to him – something we as adults may not understand, as the things that fascinate infants during this period come as second nature to us.

This is what these events are – things that, when initiated, we already know the outcome of. What goes up, must come down.

If something is hit hard enough, it will fly away.

Things like that are what your little tyke will be learning about during this developmental period as he tries causing various events to see what their outcome would be, like some sort of little scientist.

The fifth leap – Week 26 – Interactions and new depths

Mom & baby yoga classes

Now that your baby’s mental development has reached a stage where he’s mastered the art of events, it’s time for him to experiment further and see how multiple events interacting with one another behave and what their consequences are.

This will also be his most exploratory period as your child gains a level of depth perception, his vision no longer that of a cartoon as he starts to realize the various proportions of things around him, becoming very spatially aware.

This is what usually leads to the fussy periods at this halfway mark, so to speak, when a baby starts realizing his favorite things are out of reach and there’s no way for him to get said thing, making him very frustrated and tantrum-prone.

He’ll also start getting rather clingy to his mom as well, as he realizes that the sudden “increase” in relative distance between the two of you is massive for him and that you, his safe space, are so far away.

This leads him to feeling insecure, giving him separation anxiety, and affecting his sleep at times as he cannot bear the thought of being this far away from you.

The sixth leap – Week 37 – Inquiries and categories

baby getting fed with spoon

The sixth leap is a time where the baby starts noticing similarities between the everyday objects and items that he interacts with, noting what makes things unique, but also noting their similarities.

It’s a time where he starts being able to discern the differences in sounds, food, toys, and the like – a period in which he learns how to categorize things.

For instance, he’ll realize that an apple is large and sweet, sometimes green, sometimes red, while a pea is also round and green, but smaller and squishier.

He won’t really know it’s a fruit or a vegetable, but he’ll know that both of these are foods and that they taste very different to one another.

This is the developmental leap where the baby will be immersed in this world of categories, investing most of his brainpower into processing and creating these categories.

Disrupting this process will lead to a very upset baby, so try to leave his research hours unimpeded.

The seventh leap – Week 46 – A method to the madness

cute baby girl playing with musical instrument

As your baby progresses further down these baby leaps, you’ll see him begin to start doing actions that are more sophisticated and organized, things that start making some sense and have some order to them.

This is because your child is starting to understand that, in order to achieve certain plans and goals, he has to have some sort of method – steps to success.

And he’ll start doing just that.

This is the period where shape or color-matching toys are best to get, as they’ll be the most interesting to him.

This leap is a time where your beloved offspring is trying his best at understanding which block goes into which hole to finish the little puzzle laid out in front of him, and perfecting his craft.

Much like the previous period, he’ll be immersed in these activities, and offering him your help or interrupting him as he tries to wrap his brains around these things might lead to a very loud and frustrated response.

Let him have his peace and alone time, or face your baby’s fussiness in full force.

The eighth leap – Week 55 – A step in a toddler’s shoes

baby sitting in chair and drinking from baby cup

This period marks your child’s first birthday (or near enough to it) as he’s grown into quite the baby during this hectic period.


He has learned so much yet has so much still left to learn.

He might be starting to mouth simple words and even walk, giving him a new level of interaction and ways to explore.

But, what marks the wonder week this time is the fact that your child is advancing his knowledge of the methods and sequences required to reach certain results.

He starts to pair them together, understanding that a source of one event or one of these sequences can start different events, branching out into different paths and leading to different outcomes, forming so-called programs.

It’s a new skill that allows your tot to bridge the gap between his understanding of how the world works and your own, pushing him one step further toward his next developmental leaps.

During this time, it won’t be any other person who frustrates him the most.

It’s when he fails to understand how one of these events links to another that he becomes especially cranky.

You can alleviate this by being there for him and trying to explain it as best you can. He’ll welcome the assistance, especially when it comes from his own mother.

The ninth leap – Week 64 – Improving relations

2 years old girl playing with lots of colorful plastic toys indoors

Your baby is now getting well into the second year of his life and starting to develop some social skills as he improves further on these programs he’s formulated in the previous step.

He starts becoming even more physically active as he interacts with more complex things and people.

This is the period where he is at his most impressionable and will start copying what he sees other adults do, so make sure to pay close attention to who he interacts with and refrain from any bad behavior yourself.

You don’t want him to pick up on something bad, after all.

This is when he starts learning how to cooperate with others and taking his stand when it comes to simple matters and arguments, thanks to his growing eloquence and vocabulary.

Sure, it won’t be on the level of some political debate, but he’ll want his own say in the matter. This is the main reason why he’ll be fussy in this developmental leap – he’s starting to grow his character!

The final leap – Week 75 – Thinking outside the box

2.5 years old baby boy playing with lots of wooden toys block with mother

The final step occurs when your baby starts closing in on the halfway mark of his second year.

He has grown quite a lot from that newborn who saw the world as a blur and is closest to a fully functioning human being he’s been since birth.

While I do realize how silly that sounds, it is quite true.

By this point he has probably learned how to walk, is grasping some sort of basic vocabulary, and is highly aware of how things around them work.

Now that he has this understanding, he’ll start loosening up on these strict rules he’s set for themselves, growing outside of the confines as he adjusts said rules to what fits him in the most comfortable way possible.

This period of your baby’s mental development is still as impressionable as the previous one, so you should be careful and methodical about your actions as this is when your kid will start developing his set of norms that he’ll go by.

You’d want him to assemble some good ones as opposed to bad right off the bat.

And that just about does it for the 10 initial leaps for babies!

The rest of the road should be less bumpy, but your toddler should have developed the most significant life skills by now.

with the rest of his toddler years being spent perfecting his craft and expanding his horizons.

In Conclusion

These baby leaps or the wonder weeks can be tumultuous periods, that’s for certain!

And it requires a lot of hard work and effort to be put in from the parents’ side to keep their baby calm and less prone to being cranky.

The task may seem almost impossible, but, now that you know the reasons as to why this happens, I hope it ends up putting you more at ease.

As always, I hope I’ve done a good job of enlightening you and helping ease your path in the beautiful journey we call motherhood.


Frans X, van de Rijt, H., & Plooij, F. “The wonder weeks: How to stimulate the most important developmental weeks in your baby’s first 20 months and turn these 10 predictable, great, fussy phases into magical leaps forward.” Arnhem, The Netherlands: Kiddy World Publishing. 2013.

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