Progesterone levels as an indicator of pregnancy

[TwinTree]

For context: TTC for over 2 years, with low progesterone and anovulatory cycles. I had a missed miscarriage at 12+5 weeks in October 2024, and an early miscarriage last month at about 5 weeks (after conceiving on month 6 of letrozole).

When I was pregnant last month, I had 39 mol/L progesterone about 4-5 days after ovulation.

I'm waiting to test this month, but 7 days after ovulation this time my progesterone was only 39 mol/L again.

I've had a couple of symptoms similar to last month, and have been getting my hopes up (don't know if it's just because I want to be pregnant again so much). But I'm thinking if my progesterone isn't higher (relative to where I am in cycle) than last month, is that a bad sign (ie does it suggest i'm not pregnant)?

I have still ovulated very late some months even on letrozole, but I've had some higher 7dpo progesterone results previously (such as 55 and 58 mol/L).

So I guess I'm wondering if anyone has had a progesterone day 21 test in the 30s which turned out to be a (healthy) pregnancy?

I know it's not good to obsess over these things...I'm starting the process of NHS IVF soon and finding that and the losses quite tough mentally.

Thank you in advance everyone

A pregnancy wouldn't necessarily result in higher progesterone than usual on day 7. It comes from the empty follicle that has ovulated and become the corpus luteum. This is the case whether pregnant or not. If not pregnant, the progesterone starts to drop a few days later - if pregnant it will still be high. But by that time you can just do an early pregnancy test.

Thank you!