Except for the IUD, the pill and other hormonal contraceptives, which are abortifacient, contraception is different from abortion.
An environment that is too hostile can not sustain life. Here's a useful picture of the human conception to implantation timeline:
"Birth Control" pills poison the womb, preventing implantation of the week old fetus. "Contraception" is a misnomer for IUD, birth control pills, etc. as Kopp points out, it is not conception which is countered but rather implantation.