Can anyone tell me anything about this wonder week? Is it linked to walking? DD was practically running in her highly disturbed sleep, so I'm taking a punt that's what it could be (on top of the delights of teething).

I'm going to borrow my friends wonder weeks book, but in the meantime, I tried to look it up online - some sources say 51 weeks, some say 53, so I'm not sure which it is, but I assume that by this age they tend to start hitting the at slightly different times anyway.