Getting Pregnant <
Trying to conceive
25/09/2013 at 08:36
So I think I've pretty much mastered the first half of the cycle and how it works, what hormones are needed, etc. But from ovulation onwards I cannot grasp it. My understanding is that you need estrogen / LH to make the egg burst out of its sack and move into the fallopian tubes. You then need progesterone to help the lining be thick enough? And if the egg is fertilized to help it implant in your womb. If this is the case, then how can low progesterone prevent people from ovulating, as progesterone is not needed until the second half of the cycle, i.e. after ovulation has occurred?
I know I don't need to know it in this detail, but I hate not understanding things and I feel like a right numpty for not getting this!
25/09/2013 at 10:02
During your period, your hormones levels (most of them) are at their lowest. These low levels trigger your pituitary gland in your brain to make follicle stimulating hormone (FSH).
The FSH causes one (or two) follicles to start growing. As the follicles grow they produce oestrogen. A mature follicles produces a large amount of oestrogen in its final 1-2 days of growth. The large amount of oestrogen causes your pituitary gland to send out a huge surge of LH which is what you pick up on an OPK.
The LH surge weakens the follicle sac and causes it to burst and you ovulate!
As soon as the follicle has burst, it secretes progesterone. The progesterone causes the temp rise to show you ovulated, it also primes the lining to receive an embryo. A typical burst follicle produces progesterone for about two weeks before it shrivels up and dies. The falling progesterone makes your period arrive.
Then all your hormone levels are low and it causes it to start all over again!
In answer to your progesterone as a contraception, during the two week wait, when progesterone is being secreted, it tells your ovaries and brain that ovulation has happened so no more follicles are recruited to grow.
25/09/2013 at 10:03
If you got pregnant, the pregnancy hormone keeps the burst follicles alive for longer. That means it keeps producing progesterone and your period doesn't arrive.
25/09/2013 at 10:14
Thanks! That is extremely helpful Ducky. My question about progesterone was more how can it be blamed for lack of ovulation - as it typically doesn't come into the equation until after the follicle has burst (which if I'm understanding correctly, is a sign ovulation has / is occurring). I can understand it being blamed for not holding a pregnancy, but can't quite put the science together to work out how it could be responsible for anything else. Am I just being dumb here?
25/09/2013 at 10:21
Ha you're not being dumb! It is really confusing and so many little bits come into play!
The progesterone pill tricks your body into thinking it is ALWAYS in the two week wait. Your body never tries to do the first half of your cycle as it believes it has already ovulated. As your body never does the first half of your cycle, it never recruits a follicle, and doesn't ovulate, which means you can't get pregnant.
25/09/2013 at 10:25
Oooh I understand that! Thats if you have high levels of progesterone? So I guess if you had low then it would be the opposite - that your body believed it was always in the first half of your cycle? Are you a doctor Ducky, or just not as dumb as me? Haha! :)
25/09/2013 at 10:33
The amount of progesterone in the pill is 10s of time times higher than what your body can produce naturally so it will always override your natural hormones, no matter how high or low they were.
I'm not a doctor, but I used to be a human biologist and that, combined with researching all the drugs and treatments I have had over the last couple of years, means I've slowly built up a big picture of how it all works naturally (and what the drugs try and mimic/replace).
I'm dumb in other areas of life instead ;-)
26/09/2013 at 09:23
Sorry Ducky, I totally thought I'd replied to this :-( Thanks for all your help, I am a lot clearer now!
26/09/2013 at 09:45
I heart you Ducky!
26/09/2013 at 10:23
I heart you too!
26/09/2013 at 11:19
this is very interesting - thank you Ducky!!!!
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