Wonder Weeks and Fussy Periods

I had never heard the term "Wonder week" until my 2nd daughter was about a year old.  I read the Chronicles of Babywise Mom Blog and it was often referenced in there, so it piqued my interest.  What exactly is a wonder week?
 A wonder week is like a growth spurt for the brain. It happens quickly and over a relatively short period of time. And it is really upsetting to a baby. Baby's perception of the world suddenly changes and they perceive it in a whole new light. As you can imagine, it is pretty distressing and confusing for such a tiny person.
Because of this, baby may act very fussy for a short time as he adjusts to all the changes. These changes are a good thing though. They cause him to assimilate information in a new way which helps him advance in her physical and mental skills. (As a side note someone mentioned that baby's awake time tends to increase after a wonder week and I found this to be true. )

For full information, look up the book.  It is titled "The Wonder Weeks. How to stimulate your baby's mental development and help him turn his 10 predictable, great, fussy phases into magical leaps forward" by Hetty Van de Rijt and Frans Plooji.

Make sure to calculate weeks from the due date, not the actual delivery date.
Wonder Weeks and Fussy Periods:

• Wonder Week 5 - fussiness starts around 5 weeks and usually lasts 1-7 days.
• Wonder Week 8 - fussiness starts around 8 weeks and usually lasts 3-14 days
• Wonder Week 12 - fussiness starts around 12 weeks/2.8 months and usually lasts 1-7 days
• Wonder Week 19 - fussiness starts around 15 weeks/3.5 months, peeks at 17 weeks and skills appear around 19 weeks. It usually lasts 1-6 weeks **From now on Fussy periods will last longer than previously
• Wonder Week 26 - fussiness starts around 23 weeks/5.3 months, peeks at 26 weeks and skills appear around 26 weeks. It usually lasts 1-5 weeks
• Weeks 29/30 or 6.8 months - This isn't actually a Wonder Week, but many babies act fussy during this time as they begin to understand that their mommy can leave them. Just thought I'd let you know :)
• Wonder Week 37 - fussiness starts around 34 weeks/7.8 months, peeks at 36 weeks and skills appear around 37 weeks. It usually lasts 3-6 weeks
• Wonder Week 46 - fussiness starts around 42 weeks/9.7 months, peeks at 44 weeks and skills appear around 46 weeks. It usually lasts 3-7 weeks
• Wonder Week 55 - fussiness starts around 51 weeks/11.7 months, often peeks at 53 weeks and skills appear around 55 weeks. It usually lasts 3-6 weeks
• Wonder Week 64 / 14.7 months
• Wonder Week 75 / 17.2 months
• Over 20 months - Other wonder weeks have been documented throughout childhood. It is also suspected that adults even go through some wonder weeks.