21 day bloods (progesterone)

[33Carr]

Hi!
I'm having 21 day bloods done on Tuesday next week but AF is due Saturday/Sunday so it's a bit late in my cycle to be having them done. In an ideal world it would be done over this weekend but that's not going to happen!

Just wondering if it's actually worthwhile having them done or is it better to wait it out and do them at the proper timely interval next month?

Any advice or pervious experiences welcome! Thanks

21 day bloods are timed according to a 28 day cycle. From my understanding it’s 7 days before period due.

Previously, when I’ve had them done with long irregular cycles I had to get them done every week after 21 days until period occurred (21, 28, 35, 42 etc).

This time I’m getting them done cycles have shortened to 25days 🤷 and I’ve been told to get them taken on day 18. To check I’ve ovulated.

Hope that helps.

I spoke to a fertility consultant about this a couple of weeks ago and she said 7 days after ovulation, if you can work that out (since not everyone is 28 days). For my first set the day fell on a weekend so I did it on the Monday, then I had to redo them anyway to get a referral and made sure I got the day right that time (you seem to need two sets of results for that so bear in mind the time it takes if you are going the referral route). Not sure that helps really, but I would aim to get the day as close as possible if I did it again.

@PP202 @thislittlebird Thanks both for your replies. I know it needs to be 7 days before AF due, hence why I said they should get done this weekend but with all the restrictions and changes in GP services it's not possible.
Think I'll go ahead anyway on Tuesday despite being late, and then make sure it's the correct day the second time round like yourself @thislittlebird

@PP202 Also my cycles are normally around the 25day mark so I'll keep CD18 in mind next time! Thank you

Yeah I think it should be fine to do that @33Carr. I find it quite hard to pinpoint the right day for this test anyway, and I’m not convinced I’ve managed it yet (my “wrong” day before the weekend was higher than my “right” day test more recently).

@thislittlebird Yeah I can image it's mostly a rough ball park. I don't know if being a few days out will make a big difference. I don't know enough about the numbers to know what's significant

It might make a bit of a difference but hopefully not too much and will give them an idea @33Carr.