Wonder Weeks Review

A Wonder Weeks book review from the Babywise Mom. Does this book really help you know what to expect for baby sleep and behavior?

Wonder Weeks book

As you travel among social groups on the Internet discussing parenting issues, you might come across the term “wonder week.”

Something I have found interesting over the years is that certain ideas are more catching to some groups than others–even among Babywise moms. Different groups online will lean more heavily on some ideas than others. Wonder Weeks is something widely discussed and mentioned in my Chronicles Google Group.

So what is a wonder week? The Wonder Weeks is a book written by Plooij and Rijt (translated by Sonderegger). Here is the info on the book:

The Wonder Weeks describes in easy-to-understand terms the incredible developmental changes and regression periods that all babies go through during the first 20 months of their lives. 

Age-related fluctuations and the need for body contact and attention are all related to major and quite dramatic changes in the brains of children. These changes enable a baby to enter a whole new perceptual world and, as a consequence, to learn many new skills. 

Wonder week by wonder week you’ll discover the dates in the first 20 months when all babies take ten major development leaps. Learn how to encourage each leap forward. Help your baby with the three Cs’ of fussy behavior: Cranky, Clingy and Crying. Recognize the on-set of stressful times and join your children in coping with them.

Based on the scientific- and parental-world-changing discovery of a phenomenon: all normal, healthy babies appear to be more fussy at very nearly the same ages, regression periods, and sleep less in these phases, The Wonder Weeks will help your baby, and you, get the most out of these developmental phases.

In other words, there are predictable times your baby will be fussy.

Predictable Mental Leaps

All babies are more fussy than usual during each “developmental leap.” Why is this? Because baby is learning a new skill–the world is changing for your baby. Some are more dramatic (like when baby gains depth perception). This book outlines when these changes happen, what is happening, and what you can do to help ease your baby through the transition.

Baby’s mental development is growing. Your baby will have sunny weeks when things are good and calm, but during the stormy weeks, our infant’s development is on overdrive. Baby’s brain is changing and your infant is developing a new ability (or a few!).

I find the information incredibly helpful when my baby is fussy for “no reason.” When you have a baby who is normally quite happy and content and suddenly is clingy, it can be really disconcerting! But then I go to the book, and sure enough! Developmental leap happening! Baby will snap out of it as fast as she snapped “into” it. And she will come out knowing how to do more! It is helpful because if fussiness, poor eating, and/or poor sleep are due to wonder week, you don’t want to be changing up waketime lengths, dropping naps, changing how often baby eats, etc. You want to ride it out.

With Brinley and McKenna, any time they had a significant Wonder Week I included that info in their baby summary. You can see these in my posts with a label Wonder Weeks.

The argument has been made of “what about self-fulling prophecy?” In other words, when you are expecting your baby to be fussy at 19 weeks old, then won’t you see fussiness? I think that is a valid consideration. However, I personally only have a few memorized. Every time one of my babies was upset and acting “off,” I would consult and see yep, it is a wonder week. And the reason I have for my few memorized weeks is that those are the weeks I consistently get the most questions about. 

The books is about 20. The Kindle edition is about 10. And something I think is really cool that they have done is they have broken up the chapters so you can buy just one “week.” So if you are on your last baby who is 15 weeks old and you don’t think you want to buy the book for your last baby, then you come up on Wonder Week 19 and think “Ack! I need help!” you can spend $2 and buy the Kindle version for the chapter for that week. In’t that awesome? It also means you could try a chapter before committing to the whole book.

Measure By Baby’s Due Date

When looking at Wonder Weeks, you want to measure your baby’s age and the weeks based on baby’s due date.

So your little one might have had 3 months of life outside the womb, but was one month early, so you would consider your baby 2 months old.

This of course is only as accurate as your due date was accurate, so it is not always exact. There are often inaccuracies with due dates. Watch for patterns and find where your individual infant falls. You might find a baby born 3 weeks early really fits the Wonder Week leaps 2 weeks early.


Now here is what you have to be careful of. Sometimes growth spurts and wonder weeks line up. Sometimes a baby will be sick at the same time as a wonder week.

While often a wonder week can explain behavior, you want to still think through and be sure there isn’t something else going on. Sometimes you only know by trial and error. Is it a growth spurt? Try to feed and see if baby is hungry. If not, you ruled it out. So use Wonder Weeks as a tool and as a comfort, but still take into account other possibilities.

Wonder Weeks Baby App

The Wonder Weeks app is a really helpful tool to keep track of our baby and the milestones that will or should be happening. There is a leap alarm, a diary to track milestones, personalized schedules, and insights into the leaps.

The app can help you support and stimulate your baby’s development. The app has several awards including “coolest app for moms”, “Choice and gold” from mumli, “Best app for parents” from NHS, and more!

Helpful Tool for Understanding Baby

The wonder weeks is a helpful tool for understanding your baby. It will help you pinpoint the reason for sleep problems, crankiness, tantrums, and regressions. It provides practical suggestions to help your little one through these times as easily as possible, including fun games to help your kiddo with the development she is working on. It can really help make parenthood easier in baby’s first year!

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7 thoughts on “Wonder Weeks Review”

  1. My confusion with Wonder Weeks is.. is it still really considered a WW if it's been several weeks? It seems like for both ww19 & ww26 there has been unusual fussiness and sleep changes that last over a month!

  2. My baby is almost 16 weeks old and is currently in leap four. I started noticing unusual fussiness in her about two weeks ago and checked wonder weeks, and sure enough she was entering her next leap. The first week of this leap also coincided with her three month growth spurt. She has had extreme difficulty napping, and is waking once or twice early in the morning to eat. My question is: how do we continue to implement babywise during a leap? I know you said don't change anything like waketime, naps, etc., but she has already been changing them – every day has been different since this leap begun. For her naps, I don't feel right letting her cry it out now knowing (thanks to wonder weeks) all that is going on in her little mind. Any suggestions? Thank you!!

  3. My son has yet to fall into the Wonder Weeks patterns. He has never had "more fussy than usual days or weeks"…but he's just a generally happy baby so maybe fussy isn't his thing!?

  4. My 9 week old's odd behavior now for the last two nights is to stay awake from 8pm to 2 or 3 am with a few cat naps in between, maybe 30 mins. I'm certain this is a wonder week because she only comforted by being held or nursed. Day time is actually still pretty good. She is napping better than usual. I too am curious how to continue babywise during this time. I'm so afraid she will get her days and nights confused if I let her sleep too much during the day while she is up ALL night, but I know she has to be tired. Do I need to even worry about day/night confusion during this time? Proceed with babywise schedule like normal?

  5. I too have questions about wonder weeks. My first baby I hardly noticed any change at all… I implemented Babywise, it worked and we never had any issues. This second child of mine is giving me a run for my money. She used to give me good 7-8 hour stretches at night without a peep and now for 2 weeks she has been waking up just crying 4-6 times a night! I'm not sure if I should let her cry it out, if I should reinsert her pacifier. I've read so many things about sleep regression and they say don't let them cry it out, comfort them when they wake up, b/c these changes in sleep and development are hard for them… but I feel like I'm undoing all the hard work I've done up to this point. She seems to be losing all her self soothing skills. We go in, reinsert her pacifier, re-swaddle her arms down (she can't seem to fall asleep without her arms swaddled still). Any suggstions of what the "right way" is to deal with all this waking up? And the other mystery is she is not fussy during the day, she's quite pleasant! She has always struggled to take longer than 45-1 hour naps so that is nothing knew. So then I wonder, is this a wonder week or just my child learning bad sleeping habits… b/c she is so content during the day. I've really tried all my tricks (dressing her warmer, cooler, turning up the heat, down the heat, giving her extra milk in a bottle at night, feeding her around 4 or 5 am, doing the dream feed, dropping the dream feed)… ugh… I'm kind of lost now, I feel like I'VE lost all my sleep training skills.


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