Why do doctors add two weeks to pregnancy?

Question

Even if you do IVF they still add 2 weeks to how long you've been pregnant when they know exactly when you implanted and became pregnant.  And for natural pregnancies, you could track your ovulation and BD and know what day you got pregnant.
After the TWW you could get a positive test therefore be 2 weeks pregnant, right?  But it seems like they always add to the number of weeks when that's not actually true.  Why is that?

Answer

They go by length of cycle because the start of the next cycle starts the gestation period. And even if you do ivf you dont know exactly what day the egg fertilized and implanted. Conception is just a rough estimate. The tww is because your cycle usually starts 2 weeks before ovulation

Answer

They start count from the first day of your last period.

Answer

It’s standardized around the world - they go off of lmp for accurate dates. Even with IVF the timeline is going to be the same. You ovulate and your eggs are fertilized and then implanted in about the same time frame of natural conception.

Answer

If they didn’t it would go by 38 weeks from conception. It’s just hard to tell when most people conceive so they go by period because that date is known.

Answer

I was always told it’s because they are using the age of the matured egg

Answer

Some doctors don't, some do. Mine went by my actual FET date rather than my last period. Admittedly, the difference is only about 5 days for me and my protocol. Because it's so miniscule I could've gone either way with how they preferred to date it.

Why do doctors add two weeks to pregnancy?

Let’s Glow

Glow is here for you on your path to pregnancy

25+ million

4.8 stars

20+

Getting Pregnant

Pregnancy

1st Year (Baby & You)

Baby Products