3 weeks! Wow. Is it normal for a doctor to be that off on the due date?
We always thought my sister's doctor was off too. They ended up inducing her around the due date, but when my niece was born, she was COVERED in fur, had long nails and weighed 9 lbs, 10 oz.
Your niece was definitely overdue :-)
I am not sure "normal" is the word you want. A due date is an "educated guess" and depending on how accurate the mother is with knowing her menstrual history, etc., it can be more or less accurate. Having a baseline ultrasound early in the pregnancy (which I did not have) can also increase the accuracy of the date.
A pregnancy is 40 weeks, but a baby born anywhere from 37 to 43 weeks is considered term. By dates, I was at the far end (43 weeks) which is why they decided to do an induction. Actually, when my son was born, I think he was only about 1 week overdue. My daughter, on the other hand, really was 3 weeks over...I never went into labor with her because no one realized until the 43rd week that she was breech. Ooops! I ended up with a zipper (c/section) to get her out.
L