Bit confused about calculating pregnancy age. Help?

Yes you count from LMP,that is how all doctors calculate pregnancy and it will only change if an early scan showed a significant difference so you are right in saying that 5 weeks pregnant is 5 weeks since first day of last period,actual conception would have been about 3 weeks ago.

When you actually conceive you would think that's week one, but in reality doctors count week one as the week that your last period started. This is because that was the beginning of your new cycle and everything physically ( hormones, etc ) starts over at the start of your new cycle. So, yes, if you're doctor is telling you that you're 19 weeks along,, the fetal age of your baby is really 17 weeks. Most people think of a pregnancy being 9 months, right? But, in reality if you carry to full term it's 42 weeks. So, technically because the doctors start counting from the first day of your last cycle you're really pregnant longer than 9 months. This is a confusing thing that baffles most new mom's. Congratulations and best wishes for a healthy pregnancy and baby! :)

Most doctors and pregnancy websites go from the date of your last period because that is when a new egg starts preparing to be released from your ovary for fertilization. This process takes a couple weeks, of course, but that is when it all starts. I am on my 4th pregnancy and have gotten so use to counting it that way. So, going from my last period, I am 14 weeks and 5 days pregnant.

Hey you start counting from the first day of your last period. The day your are supposed to get your period u would be already 4 week prego. by the time u r a week late u would be 5 weeks prego. Hope this helps.

If you are 5 weeks pregnant, then that is from your last period. You should count from your LMP.

you count from your last period

if a girl says she's 5 weeks then she's really 3 weeks from conception!!

to caculate your due date is easy. take the date of your LMP and then add 1 week and go back 3 months. for instance, your LMP was March 10th, so then you go to March 17th, and then go back 3 months, to December 17th.

Five weeks from your LMP. Thats how they give you a due date as well.

you start counting from lmp but then once you get a sonogram done you go by your babys measurements on how far along you are.

5 weeks from last period- when you're 5 weeks pregnant it's 5 weeks from your last period