[goldstategop]

It doesn't prevent conception if not taken at the right time of a woman's reproductive cycle. And it can fool women into believing they don't have to use additional protection when having sex.

(No more Olmert! No more Kadima! No more Oslo! )

[hocndoc]

What do you mean by "right time." There's only a 5 day window when women can get pregnant.

All of this is covered in the review and backed up by the references in the links.