# Day 21 progesterone/ progesterone suppositories



## dillydolly (Mar 11, 2005)

Does anyone know if using progesterone suppositories would affect a day 21 blood test?


Also what day is best to get a day 21 blood test? I know it sounds like a stupid question but I have a longer cycle. When does progesterone peak? Is it at its highest 7 days before period starts?



Thanks


----------



## Ellie.st (Mar 11, 2005)

Hi

I don't know the answer to your first question but as far as I know, for a "Day 21" test, you need it to have it done 7 days before you expect your next period to start.  So if, for example, you have a 30-day cycle, you should get the test done on Day 23.

Ellie


----------



## jo_11 (Apr 1, 2009)

I may be too late for this thread but... You're supposed to have the progesterone test done 7 days after ovulation. It's called the 'day 21' test as this is when it would be for a 28 day cycle where ov occurs on day 14. The idea of the test is to know you have enough progesterone to support a pregnancy; at 7dpo this is when the embie should be settled in. And yes, progesterone support will affect the result.


----------

