This is really odd to me....?

Question

Why do you calculate the number of weeks pregnant you are by the date of your last period? So before the egg is ever fertilized, you are already considered two weeks pregnant.

Answer 1

It is an odd way of doing things but with this calculation it wraps a pregnancy in a perfect little 40 week package.  And most women cannot tell you for sure when they ovulated, but they usually have a good clue of when their last period was.  It makes estimating the age of the baby a bit easier

It also bases a pregnancy on a 28 day cycle, which most women do not have.  Thats why during an ultrasound, the dates will often be off.  

Answer 2

Correct. I thought it was strange, too. By the time I knew I was pregnant - I was a month the way through already!

Answer 3

Its just one of those mysterys lol. Thet acutally started counting my pregnancy when I was still a virgin which I thought was very strange lol. its just one of those things.

Answer 4

yes, basically the calculate from the first day of your last period, meaning by the time you find out, you are usually 4 weeks pregnant.

If you are confused, you're not alone. While most people talk about pregnancy being 9 months long (divided into three trimesters), most health care providers refer to a pregnancy as being 40 weeks long, starting with your last known menstrual period. You might like to know that this is also equal to 280 days, or 10 Lunar Months

Answer 5

because you can never really know the exact date of when you ovulated, it is just easier to go off your last period.  

Answer 6

Because the first day of your last period is the day your cycle starts. The day your cycle starts is the day your egg technically starts the process of going down the fallopian tubes

Answer 7

I know its weird huh.

Answer 8

Because you don't really know when you conceive. Sperm can live for up to 7 days and you can get pregnant 3-5 days out of your cycle. So you don't really know for sure when you get pregnant. Also all women have different cycles, so it is easier to use the LMP to determine dating and such. It's just what they've always done, and it really makes more sense than trying to remember when you had s*x or what days you might have actually conceived during your cycle.