This might seem weird... But I'm terrified of something going wrong when I'm pregnant..?

I'm young (18) and I've always wanted to have many children. Recently, I've been studying many different genetic diseases and am terrified that my child may aqcuire one (or that something will go wrong, like a still birth, or miscarriage). To be honest, I worry a lot by nature but this is a thought that terrifies me at night. I know I would love my child even if they had a disorder of some sort but I think I'd feel guilty. It's a weird thing, and I probably shouldn't even worry about it but I'm terrified that all the chemicals I've ingested/been around/sprayed on myself (and cloths) will cause me to have some sort of issue with conceiving a child/having a healthy baby.. Maybe I have some horrible phobia or something :S..