If your baby is more fussy than usual, their feeding is all over the place, their sleeping is inconsistent, they cry a lot more and you’ve found yourself saying “teething?” … then your little one is probably going through a wonder week. Find out what it is and how to get through it.


What is a Wonder Week?

A wonder week is a developmental leap. Kind of like a growth spurt, but for the brain.
Just like babies go through physical growth spurts, they also go through spurts in mental development.

When Do Wonder Weeks Occur?

Wonder weeks generally occur at the following times (calculated at gestational age i.e. how old your baby would be if they were born at 40 weeks):

5 weeks
8 weeks
12 weeks
19 weeks
26 weeks (6 months)
37 weeks
46 weeks
55 weeks (just after the first birthday)
64 weeks
75 weeks (just before the 18 month mark).

What Can I Expect in a Wonder Week?

  • More fussiness than normal.
  • More crying than normal.
  • More difficulty feeding, mixed hunger cues (many moms struggle to know if their baby is actually hungry, they will be difficult at the breast or refuse the bottle but still appear to be hungry).
  • Wanting to feed more often, but taking less at feeds (wonder weeks are sometimes confused with growth spurts because of the want to feed more often. Your baby actually isn’t hungry, they just want to comfort feed).
  • Wanting to be held more than normal.
  • Shorter naps and trouble going down.
  • More night wakings than normal.
  • If you’ve had a routine in the past, it may go out the window. You might think your baby needs to transition to a new routine because the old one isn’t working any more, or you may just wonder what on earth you should be doing in terms of routine now.
  • Just when you thought you had it all together, you feel like things are going backwards, or regressing.
  • You might assume your baby is teething, or is sick. You will probably consider booking a doctor’s appointment.

Why is My Baby Acting Like This?

Your baby is growing and learning more about the world around them. As new things open up to them and they are faced with new opportunities, the world can become a scary place.

For example, at the 12 week mark, one of the things babies learn is that the hands they have had fun waving in front of their faces … they can use them to grab things! What a discovery! And a fairly huge discovery to a little being who thought that waving their limbs about was the limit to their physical ability.

These new awakenings can be very, very unsettling and scary. What your little one will crave more than anything, is comfort and reassurance from parents.

How Wonder Weeks Were Discovered

Take a couple of psychologists with a theory, together with a couple of hundred families who document their baby’s happy and fussy times, day by day, from birth to 2 years old … and you have the phenomenon – ‘wonder weeks’

What these psychologists found by studying the results that the families submitted, was that all babies have fussy periods at about the same time. They go through periods of time of being happy and mostly content, but then at certain ages they will have a days or weeks of being fussy and unsettled.

These periods of fussiness include disruptions to sleeping and feeding, more crying than normal and usually moms at their wits end. More doctors appointments were scheduled during these times (maybe they’re fussy because they’re sick?) and if no medical reason was found most moms might put it down to teething.

Psychologists call these periods ‘regression periods’ (because it seems like your baby’s development is going backwards, or regressing). But in addition to studying this concept, a couple of psychologists have written a down to earth an easy to read book for parents that explain what to expect, when, and how to help your baby through their regression period. They called their book The Wonder Weeks (and it is highly recommended for every parent!)

How to Know if Your Baby is Going Through a Wonder Week

Read the book! Then, when you know what to expect and when, keep a simple chart or mark on your calendar when your baby is having a particularly happy day, or a particularly fussy day. You’ll soon start to see a pattern emerge. After a while you will be able to predict your baby’s fussy periods. Can you imagine that? Could it Just Be Teething?

Teething and wonder weeks are not related. In my experience, 80% of the time parents say their infants are ‘teething’, they are in fact going through a wonder week and not teething at all. (If your babies gums are not red and swollen their fussiness is most likely NOT teething. You’ve probably already noticed that teething gels and paracetamol aren’t helping).

Could it Just Be a Growth Spurt?

Some babies get more fussy when they are going through a growth spurt – this could be hunger or growing pain related. If your baby has had a good feed and is content, it could be a growth spurt. If they are still fussy and are not feed well (pulling off the breast, turning their head while trying to feed, refusing a bottle, drinking a little and then turning away before giving more hunger cues) then it is probably a wonder week. Hungry little babies going through a growth spurt generally (not always, but most of the time) feed well.

Could They Be Sick?

Yes, they could. If you suspect that your baby is sick, please see a doctor, don’t just put it down to a wonder week. That said, a lot of parents take their baby to the doctor when going through one of these periods but find nothing. Hello wonder week.

Buy The Book or Sections of the Book Here:

The Wonder Weeks

Image by Tom Page, used under Creative Commons License, edited by babysleepschedule.net