My Daughter Delivered 2 Weeks Ago And Was Admitted Last

My daughter delivered 2 weeks ago and was admitted last night and we found out she has an infection in her uterus. What could have caused this info I read so far not making a lot of since. She had a ok delivery. The baby did have a bowl movement (poop) then also she had a little blood coming out as she laid there in labor head nurse said she could have torn a little they didn't seem worried about it. if the infection clears up good is she going to be ok to have more kids.