Reply #48: What the MAP does [View All]

[gollygee]

It keeps a woman from ovulating and it makes the womb unsuitable for fertilization. Most of the time when women ovulate, the sperm are there waiting for the egg. Sperm cells last for a few days (roughly three), but eggs only last for a few hours.

It doesn't prevent implantation. Implantation happens a week after fertilization (generally five to ten days). If it prevented implantation it wouldn't work so well the morning after, only pretty well the next day, and be basically worthless after that. The idea is that the sperm cells only live a few days so if you can delay ovulation until after the sperm cells would die off anyway, you're safe.

A pill that prevented implantation would be useful because it would be equally effective the morning after and five days after. Then, if one pharmacist didn't want to fill the prescription, there would be plenty of time to get it filled elsewhere.

Actually, I take that back. If you wanted a pill that prevented implantation, you'd have to take it after fertilization, and have the drug in your system continually until you menstruated. If it didn't implant on the fifth day after ovulation because you took the pill on day that, the drug would be out of your system on the sixth day after ovulation and it could just implant then.