Leaps

Our research – which started in 1971 on Chimpanzees in Jane Goodalls Gombe National Park in Tanzania – led to the 10 mental leaps of a baby. We discovered that babies tend to cry more and are inconsolable at certain times without the exact cause for their distress being clear at that moment. “Why is my baby crying?”. These fussy phases occur ten times during the first 20 months of a baby: the 10 leaps of The Wonder Weeks. Learn all about the leaps in The Wonder Weeks app.

Leap calculator See leaps

Developmental leaps in babies

With every little leap your baby takes, it acquires a new perceptive ability. Because of that one new ability, your baby is now able to perceive, to see, hear, taste, smell and feel countless new things. All these things had been there in their environment all along, but prior to the leap, the baby was not able to notice them because its brain couldn’t process these perceptions yet.

Your baby will go through the first 7 leaps in the first year, while leaps 8, 9 and 10 will occur in the second year of your baby’s life.

The two phases of baby leaps

The first phase of every baby leap is called the “fussy” phase, dominated by the “3 C’s”: crying, clinginess, and crankiness. These signs reflect a sudden change in your baby’s brain, altering how they experience the world. It’s not random—your baby is upset and overwhelmed.

Each leap can bring different symptoms. Your baby might sleep poorly, feed less, become shy, or resist diaper changes. Not all babies show the same signs, and the number and intensity may vary.

Our app helps you identify which characteristics to look for during each leap. You can also track them in the app, making it easier to understand what your baby is going through and offer the right support.

During the fussy phase, your baby’s world feels unfamiliar. They want only one thing: to be close to you. You are their safe space. Your baby may cry more, want to be carried constantly, or even regress to baby-like behaviors. This clinginess can be exhausting for parents, but it’s also a sign of development.

A leap is not just about fussiness—it’s a sign that your baby is about to learn something new. After the fussy phase comes the skills phase: the exciting part where your baby puts new abilities into practice.

Leaps

The fussy phase

Each leap can bring different symptoms. Your baby might sleep poorly, feed less, become shy, or resist diaper changes. Not all babies show the same signs, and the number and intensity may vary.

Because your baby is crying and clingy during the fussy phase, as a parent you will often automatically pay more attention to your baby: you want to know what’s going on. As a result, you will notice more quickly that your baby suddenly knows more and is able to do a lot more than you expect. Your baby will suddenly attempt to do things you’d never seen it do before. Your baby has made a leap in its development!

This is the phase that parents anticipate most eagerly: the skills phase. This phase starts around the end of the fussy phase or just after its peak. At this stage, your baby has overcome the shock of the “new world” that is opening up to it. Your baby is now starting to discover the new world. Some things are completely new, other things are familiar but your baby will now experience them differently. The question is: which parts will your baby explore first? Here your baby will make its own choices. Depending on its predisposition, preference and temperament. One baby will first try out everything, while another baby may be completely fascinated by one thing and will focus on that first.

Leaps

The skills phase

"The Wonder Weeks was a game-changer for our family. It helped us understand our baby's growth and adapt to their changing needs."

Your baby leap chart in one app

Fortunately, you can prepare for a leap an know when your baby is about to begin with the fussy phase. In the integrated baby leap chart of the app, you can see exactly when your baby will start the fussy phase and the skills phase. This leap chart is based on your baby’s due date.

Why do we use the due date and not the date of birth? The brain development of every baby progresses at the same pace and starts at the same time: at fertilization. Your baby’s brain develops not only outside, but also inside the womb.

Download app

Tool

Sprünge-Rechner

Lorem ipsum dolor sit amet mauris laoreet sodales urna nulla pellentesque dictum. Elementum quisque labore dolore viverra est maecenas purus augue auctor maecenas.