questions on The Pill

I was wondering, what happens if you were pregnant but you didn’t know it and you kept taking birth control pills? Would it mess up the kid or kill it, or have any effect at all?

Also, are home pregnancy tests effective for women on birth control? If not, why specifically? (I can handle the chemistry if anyone knows it.)

depends on the pill.
some can cause foetal abnormalities (mostly feminisation of male foetuses, or adenomas in female foetuses) some don’t.
depends how long you take it before you realise you’re pregnant.
obviousl, the longer you take it, the more harm done.

and normal pregnancy tests work just fine.
they detect human chorionic gonadotrophin, a hormone produced by the placenta, the pill only increases the progesterones and oestrogens in your system.