Mine did it when I told them to do it. Mine was done on cd25 because back then I wasn't getting my LH Surge until CD17 so the doctor counted 7 days from then and booked me in with the nurse and they just did the test as normal but marked Day 25 Progesterone - due to ov on cd18. I got my results back and it was 32.8 so which meant I have oved.
You can ask them to do it whenever you get your LH Surge,,,,you just need to count 7 days from that date and book it in. Lots of girls don't ov on cd14 so I'm not sure why your doctors only do a day 21 progesterone...thats bizzare!! They just call it a 21 day pregesterone simply because the average most common cycle is 28 days.
All you have to do is make sure it is 7 days after LH Surge.
All I remember is this.....the nurse did question it and asked if it was day 21 and I told her no. So she said why not...this should be done on day 21 so I corrected her and said,....no this should be done 7 days after LH Surge and that is why this is day 25 for me because I didn't get my LH Surge until day 17 and I have to have the test 7 days from there. Well her face was very confused and I couldn't help thinking...
YOUR A NURSE AREN'T YOU SUPPOSED TO KNOW THIS....WHY AM I HAVING TO EXPLAIN THIS TO YOU!!!! jEEEEZZZZZZZZZZZZZ lol
It really freaks me out and concerns me that we have to explain things like this to the medical profession!!!!