I read it prevents fertilization: Both kinds of IUDs work by preventing sperm from joining with an egg by affecting the way they move. The hormone in Mirena increases effectiveness. It thickens cervical mucus, which provides a barrier that prevents sperm from entering the uterus. It also prevents some women's ovaries from releasing eggs (ovulation).
IUDs also alter the lining of the uterus. In theory, this may prevent pregnancy by preventing the implantation of a fertilized egg but this has not been scientifically proven. http://www.plannedparenthood.org/pp2/portal/files/portal/medicalinfo/birthcontrol/pub-contraception-iud.xml On 7/21/06, Dana Tierney wrote: > intra-uterine device, a common form of birth control. It allows fertilization > but prevents implantation. > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~| Introducing the Fusion Authority Quarterly Update. 80 pages of hard-hitting, up-to-date ColdFusion information by your peers, delivered to your door four times a year. http://www.fusionauthority.com/quarterly Archive: http://www.houseoffusion.com/cf_lists/message.cfm/forumid:5/messageid:211662 Subscription: http://www.houseoffusion.com/lists.cfm/link=s:5 Unsubscribe: http://www.houseoffusion.com/cf_lists/unsubscribe.cfm?user=89.70.5
