While condoms are the most common method of contraception, there are many other methods out there that can be used. These include birth control, the "morning after" pill, spermicide, the sponge and so many more. Unprotected sex in itself is not the cause of unwanted pregnancy. The only advantage condoms have over pills is the protection against STDs. What causes unwanted pregnancies is the ignorance and refusal to use any form of contraceptives at all. Not just condoms. As such the next resort after getting pregnant is to abort it.

So in essence, the cause of increased abortion is nothing but the willingness of people to have sex without any form of contraception