when your really 1 week pregnant why do they say 2 weeks?

Question

why do they go off your last period day instead of your conception day . i never unstood this . they say im 3 weeks but just had sex 1 week ago how is that possible at all ..

Answer 1

Because that is when your body started preparing for the pregnancy.

Answer 2

The go from the last period because it is exactly 40 weeks from your last period to the due dat, whereas it's 38 weeks from approximate date of conception. In guess 40 weeks sounds more rounded. That and most women DON'T know their conception date, but almost all women know when their last period was. The last and probably most important reason is that they're going by this CYCLE, from the time the egg began maturing for you to ovulate, rather than the time the egg was fertilized, so they're going by the egg's little life cycle. It's weird and seems really dumb, but they have their reasons.

Answer 3

most women don't know the day of their conception. Since you usually become pregnant while you are ovulating, and that usually happens 2 weeks after your period, it is easier to just tack on those two weeks, and make your pregnancy 40 weeks total. They know your REALLY only 1 week, but in order to be more accurate, they go by the last menstrual period, which adds 2 weeks, making you 3 weeks.
Confusing, i know. I tried to make it simple. I was confused myself at first.

Answer 4

Most women are not aware of the date of conception, but they do know when their last menstrual cycle began. Because of that, the medical community dates pregnancy from the beginning of the last menstrual cycle-which is, indeed, the beginning of the body preparing for pregnancy.

Most women ovulate 14 days into their cycle (mid cycle for the average 28 day cycle), and then find out two weeks later that they are pregnant when they miss their next cycle. So, you are considered four weeks pregnant (from your last menstrual cycle), but you conceived two weeks ago.

It is important for the medical community to have a standard for dating pregnancy, in order to be sure tests and such are done at the appropriate times, that the pregnancy is developing properly and other such reasons. Dating the pregnancy from the last menstrual cycle is the easiest way for them to do that.

Answer 5

They count from the first day of your last period. So when you ovulate you are 2 weeks pregnant, and 1 weeks past conception/ovulation you are then 3 weeks. Basically they count from when the follicle starts to mature the egg, which is while you are on your period.

Answer 6

because most women dont know their exact date of conception and last date of period is more concrete i guess you could say