The "personhood" amendment on the Mississippi ballot on November 8 doesn't just ban all abortions—an issue that my colleague Tim Murphy has covered quite well. It would also likely outlaw several types of birth control and possibly make all forms of hormonal contraception illegal in the state.
Mississippi anti-abortion activists want to define personhood as starting when a sperm fertilizes an egg. In that case, it would likely make intrauterine devices (IUDs), which can prevent pregnancy by blocking the implantation of a fertilized egg in the uterus, illegal. (IUDs can also prevent sperm from fertilizing the egg in the first place, and IUDs with hormones also operate much like regular old birth control pills, but that doesn't seem to matter to anti-abortion activists.)
The measure would also almost certainly make Plan B, also known as emergency contraception or the "morning after" pill, illegal. This high dose of hormones is used to prevent a woman from ovulating, but anti-abortion groups also insist that it can prevent a fertilized egg from implanting (despite the fact that scientists say there's no evidence that's the case). Needless to say, anti-abortion groups don't like Plan B very much, either.
But the law could also introduce the possibility of banning any form of hormonal birth control. Generally, "the pill" (as well as the shot, the patch, and the ring) work by stopping ovulation. But some anti-abortion groups argue that there can be failures on that front, and the doses of hormone could possibly also work by stopping implantation should an egg and sperm still manage to meet up.