What are The Wonder Weeks, and Are the Findings Reliable

When my baby was about two months old, I was introduced to the Wonder Weeks app. A basic explanation of the Wonder Week idea is that babies go through developmental leaps during certain weeks of age calculated from their due date. Each leap describes a “fussy” phase or a difficult time period a baby experiences as their brain “leaps” through new mental developments. The app describes these developmental leaps as “sudden brain changes,” that can be overwhelming for a newborn or infant. These changes can result in periods of crying, clinginess, and crankiness.

The good news, however, is that during these periods, babies master new skills like smiling, interacting, grasping, sitting up and so on. Each leap produces new skills that baby could not do before. The app discusses ten different leaps that occur over a period of 76 weeks. The leaps can last from a few days to a few weeks. The app describes the leaps as being “so great that his/her entire world suddenly looks different.” This suggests that a leap is so intense, that the world around your baby changes drastically with each new leap, making it hard for them to manage at first. Thus, this is the reason for the cranky and clingy spells.

Have you noticed that your baby’s mood changes and suddenly they seem more frightened, want to be rocked more, carried more, eat more or maybe eat less? Have you been concerned that something is suddenly wrong with your baby, but you cannot figure out what? Do you observe your baby being extremely moody one day and suddenly calm the next? Maybe it’s because of a developmental leap as described by The Wonder Weeks.


For example, my daughter is currently five months old, (24 weeks from her due date according to the app). According to The Wonder Weeks, she should be currently experiencing her fifth leap, the World of Relationships. During this leap, she may be feeling overwhelmed, cranky, seeking more attention, experiencing sleep regression, and eating less. Once she completes this leap she should be drawn to things like zippers, laces, stickers and labels. She should start imitating sounds and blowing air. She should start throwing her toys and possibly even sit up. Of course, the app states that each baby develops differently and may not master all these skills at once.

Do I agree with this? Do you agree with this? Well first, let us compare this information with how my infant is currently acting: She has been having trouble sleeping and has given up on naps completely unless we hold her. She does not seem very cranky, but she cries when we walk away from her and she has been eating a little less. Developmental wise, she has started showing interest in stickers and labels but has no interest in zippers or laces. She has begun to hold herself up while sitting but cannot pull herself up just yet. She started imitating sounds and blowing air about two months ago and has started throwing her toys.


Her previous leaps seemed to match up with her moods and she did master some new skills accordingly. But, what is the scientific evidence behind this you ask? Around the 1970’s, Frans Plooij and wife, Hetty, began a study on the interactions of mother chimps and their babies in Tanzania. Discovering that the baby chimps seemed to undergo regression periods, the couple moved on to human babies. In 1992 the findings were published. Later, they pair discovered that the infants were able to perform a group of new skills after each regression period. (

Baby Sleep Consultant, Maryanne Sayers, discredits the app when it comes to sleep regression “Any sleep/settling issues are simply just that – a sleep/settling issue…” she says in her online article, Why The Wonder Weeks Has Nothing To Do With Your Baby’s Sleep. Wikipedia claims that a follow up study done on the idea of the Wonder Weeks resulted in no findings. This and a few blogs written by some disgruntled moms were really the only debated discussion on the findings.


In my opinion, it is ironic how certain moods and milestones match up with this app. But even if they are just coincidences, the app has become a major tool for me when it comes to understanding my child through her perspective. Instead of feeling overwhelmed or frustrated when she is cranky or clingy, I know these are the times she needs me the most. As hard and overwhelming as it may be for me as a new mother, The Wonder Weeks have helped me understand that it is just as, if not more, hard and overwhelming for her.

She is an inexperienced human and she looks to me as the more experienced one to help her. Such a tiny, little being who is growing and developing in such a big world. Everyday she is processing new information, exposed to new things, and feeling new feelings. When she’s teething, when she’s tired or when she just needs to feel safe; it is so much for a baby to take in. So, she clings, she cries, she whines, and she losses sleep because it is hard for her to process big events and emotions. I thought I was overwhelmed.


In her moments of chaos, as she continues to grow, she needs me. She needs me to be the steady to her chaos and the calm to her storm.

Download The Wonder Weeks app and make your own decision on whether you think this app is reliable or not. You may not agree with its findings, but maybe you will unintentionally learn something important as a parent.

The Wonder Weeks


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: