Progesterone Level Question - Confused!?

I checked my levels 4 days after ovulation and I got a 18 ng/ml. Then I read all over the internet that the best time to check is 7 days after ovulation to get the reading at its highest, so I went back expecting to get a higher number and got 5ng/ml instead. What happened? why did it go backwards instead of forward - is this proof of no conception?

Thanks.

Thanks for your response. I am not sure how long my Lutheal Phase is. I have always had a 28 day cycle. Maybe it is time to consult a RE after 8 months of ttc and not getting much help from my OB, except for progesterone tests.

Progesterone levels usually peak around day 7. A 5ng/ml at day 7 is quite low and might mean a deficient luteal phase. I would expect you to get your period soon with those levels.

How long are your luteal phases usually? If you still have a normal length luteal phase (more than 10 days), then you are fine and either that's just how your body is or this is a weird cycle. However, if you tend to have luteal phases that are less than 10 days, it may be due to low progesterone levels. Luckily, your doctor can prescribe medication to support your uterine lining during this phase.

Just as an example, my luteal phases are typically 7-9 days and my progesterone level at 7dpo was a 7.4 (got my period the next day). My doctor prescribed me Clomid+Progesterone and I now have a 16-18 day luteal phase.

Best of luck to you and lots of baby dust!!!