Understanding Newborn Leaps: A Guide for Parents Based on The Wonder Weeks

“My baby was smiling yesterday, and today she’s fussy and clingy. What changed?”

Welcome to the fascinating (and sometimes bewildering) world of developmental leaps.

As new parents, it's easy to blame every difficult night or sudden fussiness on teething, gas, or growth spurts. But there’s another reason your newborn might be extra unsettled: mental leaps — periods of intense brain development that temporarily throw off your baby's behaviour.

This blog explores newborn leaps through the lens of The Wonder Weeks – a trusted app and book based on 35+ years of scientific research by Dutch psychologists Dr. Frans Plooij and Dr. Hetty van de Rijt. We'll help you understand what leaps are, when they happen, and how you can support your baby through each one.

What Exactly Is a Leap?

A developmental leap is a short phase in your baby's life when their brain undergoes a major transformation. They start to perceive and process the world differently — and this mental growth is as intense for them as a physical growth spurt.

Leaps often lead to:

• Sudden clinginess or separation anxiety

• Poorer sleep or disrupted naps

• Extra crying or fussiness

• Changes in appetite or feeding frequency

• A strong need for closeness and comfort

Think of leaps as your baby’s brain upgrading its operating system. It’s hard work — but it leads to incredible new abilities.

How the Wonder Weeks App Works

The Wonder Weeks app calculates your baby’s leaps based on their due date, not birth date (because brain development starts in utero). It gives you a week-by-week chart that outlines:

• When leaps are expected

• Signs to watch for

• New skills your baby is learning

• Tips to help you cope

The app uses “sunny weeks” to indicate smoother times and “stormy weeks” when your baby might be fussier due to a leap.

A Closer Look at the First 5 Leaps

Here’s what to expect in your baby’s first six months:

Leap 1: Changing Sensations Approx 5 weeks

What’s happening? Your baby begins noticing the world with more clarity — light, sound, touch, smell, and movement feel different and more intense.

Signs:

• Startles more easily

• Needs more cuddles

• Feeds more frequently

Support Tips:

• Keep stimulation low — dim lights, soft voices

• Offer more physical closeness

• Try white noise for sleep transitions

  
  

Leap 2: Recognizing Patterns Approx 7–9 weeks

What’s happening? Your baby begins to notice simple patterns in sound, light, and movement. They may start tracking with their eyes or show more alertness during playtime.

Signs:

• Fussier evenings

• Clinginess increases

• Baby may smile more or “talk” (coo)

Support Tips:

• Mirror your baby’s sounds to encourage interaction

• Try high-contrast toys and mobiles

• Stick to a calming evening routine

  
  

Leap 3: Smooth Transitions Approx 11–12 weeks

What’s happening? Movements become more fluid, and your baby begins to follow longer chains of actions. They’re starting to understand continuity.

Signs:

• Interrupted naps

• Fascination with their hands

• More hand-to-mouth movement

Support Tips:

• Offer a play gym to encourage movement

• Use songs with gestures (e.g. Twinkle Twinkle)

• Expect some sleep regressions

  
  

Leap : Events Approx 1 –19 weeks

What’s happening? Your baby begins to understand cause and effect. They may realise that swatting a toy makes it jingle or that crying brings a cuddle.

Signs:

• Major sleep disruptions (this is a big leap!)

• Increased frustration

• New skills: rolling, grabbing, longer babbling sessions

Support Tips:

• Offer more engaging toys and time on the play mat

• Sleep routines may need reinforcing with extra soothing

• Babywearing can help during clingy phases

  
  

Leap 5: Relationships Approx. 22–26 weeks

What’s happening? Your baby starts understanding distances and relationships — like that people and objects can move away but still exist (object permanence).

Signs:

• Separation anxiety emerges

• Cries when you leave the room

• Wants to be held all the time

Support Tips:

• Practice short separations to build confidence

• Use peekaboo games to teach object permanence

• Be patient – this is often the most challenging leap yet

  
  

How to Help Your Baby (and Yourself) Through a Leap

1. Respond with Empathy: Your baby isn’t “acting out” — they’re overwhelmed. Offering physical comfort and emotional reassurance builds their security.

2. Lower External Expectations: This is not the week to fix nap schedules or visit loud places. Keep things calm and predictable.

3. Celebrate the Outcome: After every stormy week comes a sunny one — often with a new smile, sound, roll, or connection. These are the magical parenting moments.

4. Track Patterns with the App: The Wonder Weeks app helps make sense of chaos. Knowing why your baby is acting a certain way can bring huge relief.

5. Join the Conversation: Talking to other parents going through the same thing makes a big difference. You’re not alone in this wild ride.

   
   

Final Thoughts: It’s Not a Regression — It’s Progress

While leaps can feel like a step backward in sleep or feeding, they’re actually a giant leap forward in development. Your baby is becoming more aware, more connected, and more capable with each phase.

The next time your little one won’t let you put them down, try to remember: their world is expanding. And you’re their safe place as they adjust.

With a little patience and a lot of love, you’ll both get through the leap — and come out stronger on the other side.