I was prescribed progesterone during my successful pregnancy with DS, the doctor had me start 2 days after IUI, and I continued until week 12.
I miscarried at the end of May last year, and was not on progesterone, even though I had asked to be prescribed it. I'm 4w2d right now and on progesterone so I'm hoping it makes a difference.
Good luck this cycle! As dairymomma said there are side-effects, and unfortunately those side-effects feel like early pregnancy symptoms. Just wanted to let you know, as it can make symptom spotting very difficult during the TWW.