How does Mirena work??

[*becstar*]

I'm so confused.

i'm terrible with how things like this actually work. Does a Mirena actually allow fertilisation but not implantation?

MODS!!! Can someone please change my title....it sounds awful

[Junglemum]

It works in the same way the mini pill does, however the dose of progesterone is not systemic but rather local to the uterus. So an egg could still be fertilised but not implant as there is no lining on the uterus due to the secretion of the hormone..

[*becstar*]

oooh sorry!! I hope to change the title...it is a bit loaded and uhh....in your face!!

so it can fertilise but not implant.....hmm...I guess that all depends of weather life begins at fetilisation or implantation???

[Junglemum]

Or perhaps life begins with the egg? or was it the chicken?

A personal thing i think. Myself? i don't have any moral issues taking the pill, using condoms, using mirena. But i am sure there are people that do.

[*becstar*]

hmmm I have had the Mirena for about 16 months now and never thought about it much. makes me a little uncomfortable though.....hmmm....

[~Raven~]

It prevents the embryo from implanting in the event that the hormone fails to prevent ovulation. I imagine that would be pretty rare though. The hormone is a constant as it's secreted internally, unlike taking the pill that can be forgotten or affected with illness or something.

It's not like the old fashioned IUD that didn't contain any hormone.

[*becstar*]

aha! thankyou

I don't have any AF so I'm assuming there is no ovulation on my part??

Thanks Raven for editing

[Junglemum]

I think it can sometimes stop ovulation but doesn't generally.

Another advantage of it being locally administered is that you don't get the nausea side effects that some women (like me!) get from the pill.

ETA- from the all trustworthy wikipedia.....

The Mirena is intended to initially release a daily dose of 20 micrograms levonorgestrel (a progestin). No single mechanism accounts for the effectiveness of the IUS in preventing pregnancy; it has several effects on the reproductive system:
Frequency of ovulation is reduced.[8]
Cervical mucus is changed to obstruct passage of sperm through the cervix.[9]
The presence of a foreign body in the uterus prompts the release of leukocytes and prostaglandins by the endometrium, substances that are hostile to both sperm and eggs.[10] Some physicians believe these substances are also hostile to very early embryos.[11]
The endometrium is thinned.[9] It has been suggested that this inhibits implantation of embryos, though no experiment has yet confirmed or disproved this theory. Because many pro-life individuals and organizations define fertilization as the beginning of pregnancy, this possible secondary mechanism of action has led some pro-life individuals and organizations to label the IUS an abortifacient.

I didn't know about the obstruction of sperm, or the increase in leukocytes and prostaglandin production. Not that it changes my opinion, just find it interesting.