You can't sub for a prenatal test. There are specific hormones in a pregnant women's urin and chemicals and ish. That would just be moronic and they're either think you're not pregnant or are subbing.

Hon, I'd dilute as much as possible as subbing isn't an option. But it also depends on when you last smoked, if it was around a month ago you should be fine..the longer the better. Keep us updated!