Lucia,
I'm not sure whether this will help you because really no one ever tested me it was always ever done by predicting when bleeding was happening my progesterone was low.
1st Preg All IVF, Was on progesterone for 2ww and then once positive stopped began to bleed at 6 weeks ( put on bedrest and then given progesterone again bleeding stopped) went to Obst as FS didnt do Obst continued to bleed on and off till 16 weeks where the pregnancy became unviable due to PROM.
2nd Preg IVF again continued 2ww with progesterone this time FS did Obst kept me on Progesterone till 8 weeks no bleeding but again PROM happened at 20 weeks
3rd Preg IVF 2ww progesterone and then continued till 13 weeks the last one taken the morning of my surgery to stitch my cervix closed. No bleeding no problems at all, the progesterone sustained the preg till the placenta was fully formed and could do the work itself.
I will be taking progesterone again for the same reason I dont want to lose another baby, if it helped great if it didnt do anything great didnt really effect me by taking it.
Good luck
Bec
BTW the obst that did my 3rd preg was a high risk specialist so you would think he might want some scientific reason to give me progesterone but he said to me we are not taking risks , and when I needed a script for 3 pessaries at the end I said well I will stop today and he was adament to keep taking it till that 13 weeks was up