main.min_jhxetk.js Baby’s first 4 leaps in mental development – Newborn Baby
Baby’s first 4 leaps in mental development

Research spanning over 35 years into the development of babies has found that all normal and healthy babies go through predictable phases of fussiness. These difficult phases, called ‘the wonder weeks’, can lead parents to despair. Babies cry more, become clingier, and crankier (what the Wonder Weeks authors describe as the three Cs), but there is a good reason for this.

A baby’s brain undergoes sudden and drastic changes, which alters the way they perceive the world. This can be frightening and confusing for them, but these brain changes are a sign of progress. Your baby is learning new skills, so as challenging as these periods are, they are temporary and cause for celebration.

The following is a summary of the first 4 leaps in mental development that all babies go through in the first 6 months of life. Here we outline what each of these leaps mean for your baby’s understanding of the world around them, how they use this understanding to develop new skills, and how you can help them.

Your baby’s first 4 leaps in mental development

Understanding these leaps and being prepared for a fussy baby will help you cope through these times, and give you the tools to support them through it when they need it. Each leap in development is made up of a Brain Change, The Fussy Phase, The Magical Leap Forward, followed by The ‘Easy’ Period.

Leap 1: The World of Changing Sensations

When: Around four to five weeks


  • Crying real tears for the first time
  • Staying awake for longer periods
  • Increased alertness

What’s happening The senses are going through a period of rapid growth. For example, they can focus on objects further away now. They suddenly see, hear, smell, taste, and feel in a completely new way.

How to help Offer support, comfort, and opportunities to discover new things. Experiment to see which activities they enjoy. Chat with them often, and let their responses guide you. Be careful not to overstimulate them, and give them plenty of breaks. Here is how to recognise and respond to newborn cues.

After the leap At around 6 weeks, your baby may be more cheerful and alert.

Leap 2: The World of Patterns

When: Between seven and nine weeks


  • Your baby may discover their hands and feet
  • They might be making short bursts of sounds
  • Almost all babies cry more often now, characterised by the three Cs
  • You might notice they become shy around strangers, lose their appetite, cling to you more, or sleep poorly

What’s happening Your baby will start to see patterns in the world around them, and also begin to distinguish patterns with all of their senses. Changes like this, as with the first leap, can make them feel confused and bewildered so they need time to adjust.

How to help Plenty of close physical contact helps to calm some babies. You are their secure base, and they need to feel safe before they want to discover the world again with the help of their new skills. Show your baby things around the house at different distances, offer variety in toys, views, and sounds (you might notice they start to get bored now), help them discover their hands and feet, encourage them to grab toys, and encourage and respond to sounds they make. Allow opportunities for independent play. 

After the leap Around 10 weeks, your baby might not demand as much attention as before, becoming more independent. You might find your baby more cheerful and easygoing.

Leap 3: The World of Smooth Transitions

When: Around 11 or 12 weeks, or almost 3 months


  • Your baby’s jerky movements will start to change and become more fluid
  • Crying more often and for longer periods than before
  • More demanding for attention again
  • Shy with strangers, clingy, and loss of appetite
  • Many overnight wakings, or nap refusal
  • They may seem quieter or less lively than usual


What’s happening As they enter this new world, your baby is able to recognise smooth transitions in sights, sounds, tastes, smells, and touch. Their sight has improved so much that it is almost like an adult’s.

How to help The more your baby plays or experiments with a new skill, the sooner they’ll be able to master it. Encourage them to practice new skills, to use their new voice (you might hear high-pitched shrieks), chat with them, respond to their communication attempts, teach your baby to reach and grasp toys, allow them to play without clothes on, and encourage them to roll.

After the leap At around 13 weeks, you might notice how cheerful and active your baby becomes. They’re like a little person now.

Leap 4: The World of Events

When: Between 18 and 20 weeks, or 4 ½ months


  • During the fussy phase, they will cry and whine more
  • They might show a caregiver preference
  • Expect to be amused more
  • They may sleep poorly (see ‘Four month sleep regression, or is it?’, lose their appetite, and be moody
  • You may need to support your baby’s head more often now

What’s happening After the last leap forward, your baby was able to see, hear, smell, taste, and feel smooth transitions, but all they could understand is one smooth transition, for instance, grabbing a toy. Now, they might be able to repeat that movement, or grab a toy with one hand and then try to pass it to the other.

How to help Your baby is probably very interested in everything going on around them, so give them the chance to practice with their hands and fingers, to explore, to listen to music, to play games such as ‘peekaboo’, to read books with you, and show them new things to look at.

After the leap Around 21 weeks, another period of calm emerges. Your baby might have a lot more energy, and require more independent play.

Stay tuned for the next developmental leap, Leap 5: The World of Relationships (hello separation anxiety!), which appears around 6 months. Read more about it, and the following leaps in The Wonder Weeks – A Stress-Free Guide to Your Baby’s Behavior.

Note: You might feel exhausted, worried, exasperated, and overwhelmed during these fussy phases. Trust your instincts and ignore advice to be stern with your baby. The best thing you can do is comfort your baby. If you’re struggling, please speak to a professional or get some in-home support if possible.

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