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[Pollie]

Hello

I don't really understand why some women's periods stop altogether and others just become lighter when using mirena coil?

Is it to do with the amount of oestrogen a woman produces naturally from her own cycle?  I mean if a women has high oestrogen levels then to stop periods completely requires a higher level of progestogen than delivered by mirena ?

Is it to do with how heavy your periods are before you have mirena fitted ?

Why do some women have heavy periods not others - higher oestrogen levels?

Sorry so many questions 


Thanks for any info or experiences

Pollie

[dahliagirl]

The progestogen in the mirena is delivered directly to the lining of the uterus and causes it to atrophy.  It should not interfere with the rest of the reproductive system.

I was looking at information about mirena and although a lot of people keep saying it stops periods all together, I think they overstate it.  When you look at the figures it is only about 60% of women period free after 2 cycles of mirena (ie 10 years!)

[Pollie]

Having looked into this further I now read that the Mirena "partially suppresses ovulation'.

"Partially suppresses"

What on earth does this mean

Can anyone throw any light on this ?

Pollie

[Briony]

Haven't a clue, but like you, would love to know the answer! X

[Hurdity]

I really don't understand this Pollie - I mean ovulation either happens or it doesn't surely?!

On the actual website for Mirena it gives this as the explanation for how it works ( in lay terms):

Mirena is more than 99% effective at preventing pregnancy for as long as you want for up to 5 years.

Mirena prevents pregnancy, most likely in several ways:

• Thickening cervical mucus to prevent sperm from entering your uterus

• Inhibiting sperm from reaching or fertilizing your egg

• Thinning the lining of your uterus

While there's no single explanation for how Mirena works, most likely, the above actions work together to prevent pregnancy for up to 5 years.

http://www.mirena-us.com/about-mirena/how-mirena-works.php

From this I would infer that it suppresses fertilisation and prevents implantation in the unlikely event that fertilisation occurs. Maybe there is new information elsewhere about its mechanism of action?

Hurdity x

[Pollie]

Hurdity - what you have written above was the limits of my knowledge at the time I had mine fitted. It is all that my GP and NHS website had to say on the matter, I was not aware that ovulation may not occur. However some basic googling now reveals;

From the Mayoclinic.org

http://www.mayoclinic.org/tests-procedures/mirena/basics/definition/prc-20012867

Mirena also thins the lining of the uterus and partially suppresses ovulation.

From an American Research Institute

https://www.pop.org/content/mirena-iud-becoming-more-popular-and-lawsuits-are-piling

Mirena, it is true, is more than just an IUD. It also contains a synthetic “hormone” called levonorgestrel that some months prevents ovulation. Even when what is called “breakthrough ovulation” occurs, the progestin sometimes still prevents conception by thickening the cervical mucus and preventing sperm from reaching the ovum

I guess on reflection  'partially' means 'occasionally' (poor American grammar) 



Any thoughts ?

Pollie

[Hurdity]

Hi Pollie - limits of my knowledge too! I expect you're right - ie partially means sometimes/occasionally.

I saw the Mayo clinic blurb too but thought the manufacturer's website would have the right info - albeit simplified.

Ha! Just found this! Eureka!

Ovarian function

During the first year of use, some women experience suppression of ovarian function. Thereafter, most cycles are ovulatory22 and the incidence of ovulatory cycles with Mirena and with the Cu-IUD is the same (85%)18. The effect of LNG on ovarian function depends on plasma LNG levels and there are marked inter-individual differences in the plasma levels achieved22,23. In general, the anovulatory cycles (5–15% of treatment cycles) correlate with higher levels of LNG18,24.

For complete suppression of ovulation, a daily intrauterine release of more than 50 µg of LNG is required23. With Mirena, only 20 µg/day LNG is released. Determination of plasma estradiol and progesterone (P) levels indicates that women using Mirena generally have normal ovulatory cycles25,24. Other types of ovarian function that may be exhibited by women using Mirena include: anovulation with some inhibition of estradiol production; anovulation with high follicular activity; and ovulation with an inadequate luteal phase24.

There is no reduction in E2 levels during the use of Mirena. Figure 4 shows the mean plasma E2 and LNG concentrations in menstruating and amenorrheic women23. Menstrual bleeding does not itself reflect ovarian function among women using Mirena: not only are average progesterone levels the same among those with regular, scanty bleeds as those with oligomenorrhea, but the levels of E2 and the incidence of ovulation are similar for the two groups22.

http://www.mirena.com/en/professional/indications/contraception/how_does_mirena_work/index.php#

You will probably find answers to some of your initial questions also on this site.  Happy reading!

Hurdity x

[Pollie]

Thank you so so much that is just great ! It it definitely the detail that I have been looking for. I have read it quickly and am now going back to it to absorb and understand it !

Thankyou

Pollie
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