Has anyone had this type of bloodwork done ?

Hi I’m curious if anyone has had this type of bloodwork done before, my gynecologist had me go for blood work yesterday, To test for Anti-Mullerian Hormone (AMH). It test for ovarian reserve. What exactly is it and what do they tell from this ? We have been trying for baby #3 since March after a MC in February at 6weeks, never needed a D&C thankfully. I’m 36 so I didn’t know if it’s required to run that bloodwork? Any information would be great! They said this lab work could take a little bit.