Okay I'll bite.
Radiation makes men sterile. She is sleeping with men drinking irradiated booze...ergo, no pregnancy.
Furthermore, crude abortion methods have basically been as timeless as prostitution ("the oldest profession"). I'm sure there are ways to...terminate unwanted circumstances.
Skirt speaks truth.
But then again, Nova could have a hostile fetus/ovary or whatever its called
I remember when I had to go get x-rays to check for _____ and the doctor gave me the underpants rag thingy to protect my "reproductive organs". Wait, you didn't need to know that.
Maybe she takes pills. I also heard from a mate that during the acient Egyptian times, prostitiutes pushed. . .ah, large rocks to kill the baby...but I doubt Nova would do that.
Puh! I'm just gonna shut my trap now. . .