Consent to sex is consent to the risk of pregnancy. Vasectomies can fail, condoms can fail, birth control can fail. You go in with the understanding on BOTH SIDES OF THIS EQUATION that pregnancy is a real option and you accept that responsibility. The existence of abortions and such other measures is a separate conversation but consenting to sex with someone who has the capability to create a fetus with you is the same as consenting to the possibility a fetus could be formed