I thought everyone would like this site I came across today:

IVF Pregnancy Due Date and Fetal Development Calculator
go to: http://ivf.ca/calcu.htm

I didn't realize that one is 4 weeks preg at time of beta. Interesting calculator and includes fetal development stages/dates.

Good luck and for all!

Rhonda (42) DH (36)
TTC #1 3 years
3 natural BFP- all m/c at 6-8 wks
1 cancelled IVF (own cycle)
DE-IVF Aug08