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How to Handle Wonder Weeks With a Premature Baby

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There are many unknowns when you have a premature baby.

Will there be NICU time?

Will your baby be behind developmentally or will they meet regular milestones?

And what about growth spurts and wonder weeks?

There are many things I could talk about regarding the topic of premature births, but today I want to focus on how to handle the wonder weeks with a premature baby.

wonder weeks premature baby

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What Are the Wonder Weeks?

First off, what the heck even are the wonder weeks and why does it make a difference if your baby is born premature?

I’ll explain both! The Wonder Weeks is a term coined by two Dutch doctors, Dr. Frans Plooj and Dr. Hetty van de Rij.

The Wonder Weeks are used to describe mental leaps in a baby’s development.

You can think of leaps as growth spurts, but for the brain.

When your baby is going through a ‘leap’ it is because something new is going on in their brain and it will lead to them developing a new skill.

Unfortunately, it also causes a lot of fussiness.

It’s as if your baby suddenly sees the world in a whole new light, and that is scary!

It’s also probably very frustrating for your baby to not have control over something they used to have control over.

Although the fussiness caused by leaps can be tough, it’s so worth it to see your baby learn new skills.

Read –> Do Preemies Need More Sleep? How Much Sleep Your Premature Baby Should be Getting

When Do Wonder Weeks Leaps Occur With a Full-Term Baby?

The leaps during the wonder weeks occur based on your baby’s adjusted age. For a full-term baby, the wonder weeks occur between 4 weeks and 20 months through your baby’s life.

  • Wonder Weeks Leap 1: week 5
  • Wonder Weeks Leap 2: week 8
  • Wonder Weeks Leap 3: week 12
  • Wonder Weeks Leap 4: 15-19
  • Wonder Weeks Leap 5: 23-26
  • Wonder Weeks Leap 6: 33-37
  • Wonder Weeks Leap 7: 42-46
  • Wonder Weeks Leap 8: 52-55
  • Wonder Weeks Leap 9: 61-64
  • Wonder Weeks Leap 10: 72-76

Are the Wonder Weeks Accurate?

The leaps in the wonder weeks can definitely have some ebb and flow during the timing.

Babies are all so different and their development and brain growth definitely vary.

There is also the issue that your due date could be off!

Because of these two reasons, leaps can happen up to a week late or early.

The weeks are just an estimation to go off of, although they were extremely accurate with my singleton!

When Do Wonder Weeks Occur With a Premature Baby?

The actual date of the wonder weeks leap is based on your baby’s adjusted age, NOT their actual age.

What is Adjusted Age? How to Calculate Adjusted Age Vs. Actual Age

wonder weeks premature baby

Actual Age: Actual age is your baby’s actual age, regardless of whether or not they were born full-term or prematurely.

Adjusted Age: Adjusted age is your baby’s age based on their due date.

So, if your baby was born 4 weeks early, then 6-weeks past birth they will be 6-weeks old based on actual age but only 2-weeks old based on adjusted age.

So technically, on paper, your premature baby will experience the wonder week leaps on the same date as if they were born full term.

Does Adjusted Age Matter?

Adjusted age absolutely matters for the first 2-years of your child’s life. By the age of 2, they should be caught up developmentally.

But until then, they won’t be considered ‘behind’ with speech, crawling, or any other milestones.

Read –> Bringing Home Preemie Twins: How to Adjust to Life at Home After the NICU

Adjusted Age and Wonder Weeks With a Premature Baby

If your baby is 4 weeks premature, they will experience leap 1 around the actual age of 9 weeks instead of 5 weeks. This is 5 weeks past their due date.

It can be confusing but the science behind it is simple: a preterm baby’s brain isn’t going to be fully developed.

My twins were 8 weeks early, and at 8 weeks old, still acted exactly the same as a day old newborn.

Actual age vs. adjusted age was confusing to me when my girls were first born, so I’m going to put it right here in bold letters!

Actual age is how old your baby actually is. Adjusted age is the age based on your baby’s due date. Since my girls were born 8 weeks early, at 10 weeks their actual age was 10 weeks but their adjusted age was 2 weeks.

You can read the wonder weeks book or download the app to see the complete timeline of leaps, and fantastic tips on how to handle them.

Wonder Weeks and Premature Babies: My Experience

You can read all of the scientific information in the world, but nothing compares to real-life experience, amirite?

My singleton was full-term (actually, he was 4 excruciating days late!) and he hit the wonder week leaps right on the dot.

My twins were born 8 weeks early and spent just under 3 weeks in the NICU. Right around their due date, I plugged their information into the Wonder Weeks App.

I fully expected them to hit their leaps right around their adjusted age because everything I read said that the leaps were based on adjusted age.

My twins hit their leaps about 2 weeks earlier than they were supposed to.

The first leap occurs around week 5 and for their adjusted age, that would put them at 13 weeks. They both hit the leap right around 11 weeks and this trend continued for just about every leap. 

This just goes to show that all babies are so incredibly different, especially preemies! My advice is to know when the leap should happen according to their adjusted age, but not to be shocked or concerned if things are off.

Who knows, their due date could have been off, or their brains developed at a faster pace.

identical twin girls with arms around each other.
My identical twin girls at 3.5. They were born 8-weeks early, and are perfectly healthy, well adjusted little girls now!

Premature Babies and Development

While my girls experienced the fussy part of the leap early, they typically didn’t master skills anywhere close to the leap. It took them a really, really long time to master new skills.

If you have a preemie and are concerned about their development, please try not to worry! Take them to any developmental follow-up appointments that are suggested and continue to work on things, but don’t stress it if they aren’t reaching their milestones.

When I was pregnant with my twins, a fellow twin mom gave me a really good tip.

She said that premature babies will be behind developmentally until around the age of two. This was definitely the case with my girls!

At their two-year checkup, they were meeting all of the milestones of a two-year-old, and were even ahead in speech!

I hope this post was helpful for understanding wonder weeks when your baby is premature! And from one preemie mama to another, please feel free to reach out if you have any questions!

P.S. Make sure you’re following me on social media to keep up with our family and all the twin cuteness! I am on Instagram, Facebook, and Pinterest!

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Monday 15th of May 2023

my twins were born 6 weeks early. they were 2 weeks adjusted age last Friday and for the last 2 days at least have been exhibiting lots the many signs of the wonder weeks. is it fair to say they are experiencing the fussy period even though they arent 5 weeks old yet.

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