No, an I'd should no make you infertile, it is there to prevent pregnancy. I had the mirena Iud in for a year before having it removed to conceive my 4th baby. Fertility is meant to return pretty much right away with this Iud. For some women they can fall straight away, but it can take up to a year. For me I took 6 months of trying before I fell pregnant, not sure if coincidence but the month I fell pregnant I was using a gel called conceive plus during my ovulation time.
I had my IUD removed Dec 27th, and got a positive pregnancy test Feb 12th. So about 6 weeks. I had one period between when I got it removed and getting pregnant.
It took me 10 months after having the Mirena removed.