The Physiology of the Female Menstrual Cycle

[Thomas the Rhymer]

I think that you fairly thoroughly explained the fertility periods, which seems to have been a much better explanation compared with the charts and even some of the other scientific information that is put out for the public. From some of those charts, we were getting the sense that a woman had a peak period of fertility during the middle of her cycle (between menstruations) and both before and after her period were supposedly "safe periods" to ejaculate within her without worries of pregnancy.

...

I do understand as well that some sperm can still be in the pre-ejaculation fluids, and I kind of wonder about how much sperm is potentially in pre-ejaculation fluids. Is there any reliable and well though out studies that get into the details of pre-ejaculation fluids or looking into whether guys really are successfully pulling out before any actual ejaculation fluid gets into the girl?

Thank you for your questions and comments.

With regards to your first comment: Thanks for bringing this up, I completely forgot to discuss this aspect. Although a woman can fall pregnant with a fertilized egg anytime before the next period, unfertilized eggs are thought to die within 48 hours.

The ovary will release an egg at ovulation, but sometimes less dominant follicles will release another egg after the first one, even up to a few days later. (That's how you get non-identical twins)

So if you wait for all the potential eggs to die off, you can then safely release sperm into her without causing pregnancy.

Timing the egg die-off is so notoriously unreliable that it is not recommended; it's safer to assume she can fall pregnant anytime before the period.

With regards to your second comment, please see this post and the follow up discussion:
https://www.rooshvforum.com/thread-18970-post-345530.html#pid345530

For a deeper discussion of contraceptive methods:
https://www.rooshvforum.com/thread-40893-post-842604.html#pid842604

 

[Thomas the Rhymer]

Some more questions:

-I've read many times that women are the most fertile 2 days before and after the 14th day of their period, I assume now that this is mainly said because the 14th day is just an estimate + the fact that the sperm can stay alive, hence 2 days before ovulation is still dangerous, because if we were certain to know when a girl would ovulate and disregarding the sperm can stay alive fact then 1 or 2 days before ovulation she would be infertile correct?

-what info do you have on mood changes during various phases of the cycle. We generally know many girls are hornier during ovulation and crankier during menstruation. What else can you tell us? Also my current girl is on her best behavior during menstruation actually and the worst the 1-2 days before she starts bleeding. She might be a special case. From my experience girls are the horniest during both menstruation and ovulation, although in the former they will be more resistant due to the messiness.

-does alcohol affect the chance of impregnating a girl (alcohol on the men and/or on the females side)?

-is there any scientific evidence that girls are more likely to get pregnant when they are really into the guy? I've heard also when the girl has an orgasm the chance increases correct?

And not sure if you have good info on this, but if you do, feel free to share. How does the pill influence female psychology?

With regards to your first question: assuming that a woman has a textbook 28 day cycle (which doesn't really exist) and assuming that a woman releases only one egg at ovulation and does not have any follow up eggs, then she will ovulate at day 14, and by day 16 the egg will have died if it has not been fertilized. Since a woman can release follow-up eggs after the first one, and since most women's cycles are not really 28 days, that model is an oversimplification.

Second question: there is a pre-ovulation syndrome and a pre-menstrual syndrome. The exact symptoms/signs of the syndromes vary between individuals, but in general: pre-ovulation is accompanied by better mood, need to socialise, flushing of the lips and cheeks, breast and buttock enlargement, increased vaginal fluids. Pre-menstrual syndrome is accompanied by irritableness, mood swings, bloatedness, constipation, and genital dryness.

The exact causes of these syndromes are thought to be due to the effect of peak blood oestrogen for pre-ovulation and due to the peak and fall of progesterone levels for pre-menstrual syndrome. That said, pre-ovulation and PMS are both very poorly understood and the exact mechanisms underlying them have not been discovered. The person or team that discovers exactly what PMS is on a biological/cell level could very well win a nobel peace prize, because it has remained a stubborn mystery for a while now.

Third question: strictly speaking, alcohol is toxic to sperm, so technically it should reduce the chances of pregnancy; but realistically speaking, alcohol increases the chance of having unplanned unprotected sex, so it balances out. On the females side, alcohol may destroy the egg if there is a high enough concentration at the uterine wall, but that will have to happen several days after fertilization, when the egg tries to implant itself.

Put it this way: despite being toxic, alcohol seems to cause more pregnancies than it prevents.

Fourth question: A girl who is into a guy or who is having an orgasm will release vaginal, cervical and uterine fluids which are very sperm friendly, containing lots of nutrients for the sperm to eat, lots of water to make it easier for the sperm to swim, and very few defense mechanisms to prevent killing of sperm. So yes, this can increase the chances of pregnancy, but it is not a requirement.

If you are more interested in sperm and how they get to the egg, this is a great introductory video:


Fifth question: the female contraceptive pill works by suppressing the release of either LH or FSH. Without these hormones, follicles cannot mature their eggs and also cannot release their eggs. This is done by maintaining high levels of progesterone and/or oestrogen in the blood stream, which shuts down the brain's desire to create LH or FSH.

Other effects on physiology depend on the woman, and there is a great variation in effects, but commonly: improvement in skin (this is due to high hormone levels cancelling out testosterone effects), bloating, constipation, water retention, mood changes, personality changes, weight gain. Most of the bad side effects on a woman's body are due to the effects of Progesterone, which causes water retention.

There is also some conflicting evidence with regards to some cancers, but if a woman develops a hormone responsive cancer, she may make it worse by being on the pill. The pill also speeds up blood clotting, which in some women can cause thrombosis, especially if they are also smokers.

 

[Thomas the Rhymer]

Great write up. In my experience girls get incredibly horny the first few days of their period. I have heard this from girls I have dated, female friends, and guys who said the same thing.

Why is that? Any idea? From what I understand, if I read this correctly, the first two or three days of her period would be when she isn't fertile because her fertility window just closed. So, why horny?

Women are just weird. Maybe they feel excited because they know they won't fall pregnant.

I've had the opposite experience, personally.

 

[Papaya]

I remember reading old biblical texts that say one shouldn't be around a woman when she has her period or let her cook food.

I've known a few that rule applies to the other 3 weeks of the month as well

 

[Bad Hussar]

Thanks for the right up TtR. Very informative.

So a woman who is very attuned to her body can "know" that she is highly fertile starting from when she experiences cramps up to the time she menstruates? And somewhat fertile for as long as 7 days before the cramps because of the long shelf life of sperm?

TtR, do you have any thoughts about how evolutionary factors influence which egg ends up being fertilised? With sperm there are zillions, and it is clear there is a sort of battle between them, and the most "fit" end up fertilising the egg. Do you think something similar happens with eggs? There are obviously far fewer eggs, but even if a woman is constantly pregnant during her lifetime only a small portion of her eggs will be fertilised. Is there any indication of a selection mechanism that allows the most fit eggs to be the ones that are fertilised?

 

[Thomas the Rhymer]

Thanks for the right up TtR. Very informative.

So a woman who is very attuned to her body can "know" that she is highly fertile starting from when she experiences cramps up to the time she menstruates?

My general experience of women are that they tend not to be very aware of what's happening with their bodies, but technically, a woman may be able to know if she's about to ovulate.

And somewhat fertile for as long as 7 days before the cramps because of the long shelf life of sperm?

She will be 'highly' fertile from before 7 days of ovulation (and by ovulation, I mean the release of the dominant egg from the dominant follicle) until 2 days after ovulation (the dominant egg will die within 2 days if not fertilized). Sex during this window gives the greatest chances of fertilization. She will be somewhat fertile after the death of the dominant eggs because non-dominant eggs may still be released afterwards; all the unfertilized eggs should be dead after a few days and technically the chances of becoming pregnant become less and less as time passes from the initial release of the dominant egg. This is both because the supply of eggs dries up and due to the sperm-hostile effects of progesterone. However, the possibility of pregnancy exists as long as the endometrium has not died.

TtR, do you have any thoughts about how evolutionary factors influence which egg ends up being fertilised? With sperm there are zillions, and it is clear there is a sort of battle between them, and the most "fit" end up fertilising the egg. Do you think something similar happens with eggs? There are obviously far fewer eggs, but even if a woman is constantly pregnant during her lifetime only a small portion of her eggs will be fertilised. Is there any indication of a selection mechanism that allows the most fit eggs to be the ones that are fertilised?

Yes,

First of all, the process of atresia kills off many of the weaker eggs. Recall that a woman is born with 7 million eggs but only has a fraction of that left by the time she hits puberty, and the die-off carries on until menopause. It is thought that the weaker eggs end up dying off.

Secondly, the eggs themselves need to be sensitive to the effects of FSH and LH in order to mature into a state where they can be fertilized. A defective egg may be unable to respond to the effects of these hormones and therefore will not be able to 'ripen', and fertilization should technically not be possible.

 

[Alpha_Romeo]

Bloody hell.

How is it that you know all of this? Are you an OBGyn by trade or is it that you are just passionate about your... hobby?

 

[Thomas the Rhymer]

Bloody hell.

How is it that you know all of this? Are you an OBGyn by trade or is it that you are just passionate about your... hobby?

I am a doctor. General practioner/family physician. Last year I was also lecturing in reproductive physiology, so the post was compiled out of my lecture notes. I can do male physiology too, if there is demand for it.

 

[WildBoar]

Testosterone in women also does not follow a cycle. It is made at a constant level, and even persists beyond menopause.

I've read that testosterone rises during the latter part of week two. It tends to make women more impulsive, daring and seeking sexual intercourse. Which makes sense as it's during ovulation.

And before and during menstruation, testosterone is relatively higher than the female hormones, which makes women aggressive and moody.

The funny thing with humans is that the female menstrual cycle does not influence testosterone concentrations, which is an interesting subject to speculate with in regards with evolutionary psychology.

Very informative thread, btw, thanks!

 

[JayJuanGee]

Bloody hell.

How is it that you know all of this? Are you an OBGyn by trade or is it that you are just passionate about your... hobby?

I am a doctor. General practioner/family physician. Last year I was also lecturing in reproductive physiology, so the post was compiled out of my lecture notes. I can do male physiology too, if there is demand for it.

Could be a bit of work for you Thomas, but I'm sure if you wrote a post on male reproductive physiology, then many guys would be interested in reading your take on that subject matter.

You have a real good way of describing the science in an understandable manner, and possibly, you could throw in a few gaming scenarios and guy lifestyle matters that may clear up some of the bro-science... maybe link it here too, if you are still willing to put something together, in order that subscribers to this thread will get an alert...

 

[Sooth]

Women are baby making machines.

 

[Nascimento]

This is one hell of a datasheet. Bump.

One question:

Say you have sex with her exactly when she's ovulating, and you blow inside or fail to pull-out correctly. So you get her a morning after pill a few hours later or the next day and have her take it.

Obviously it's never 100%. But considering it is her most fertile moment where you came inside, how effective is the pill at preventing pregnancy?

 

[Thomas the Rhymer]

This is one hell of a datasheet. Bump.

One question:

Say you have sex with her exactly when she's ovulating, and you blow inside or fail to pull-out correctly. So you get her a morning after pill a few hours later or the next day and have her take it.

Obviously it's never 100%. But considering it is her most fertile moment where you came inside, how effective is the pill at preventing pregnancy?

Even if she falls 'pregnant' at the time of sex, it still takes a while for the pregnancy to implant. The morning after pill can prevent this implantation, which basically kills the pregnancy - in essence, a very early chemical abortion.

If implantation has already occurred, the pill will not work. Implantation does take about 24 hours to occur after fertilization.

The exact numbers are unknown (no one has a done a double-blind randomised trial on the matter) but available evidence suggests that the risk of a woman falling pregnant will be reduced by 95% if she takes a morning-after pill within 24 hours of unprotected sex. Efficacy begins to drop thereafter.

 

[Nascimento]

Thanks for the reply. This is great to know.

 

[polar]

Thomas: thank you for this write-up.

Question on spermicide: could you please advise how effective it is in preventing pregnancy - how it works, effectiveness if woman is not on any other birth control, safety if coming inside her with only spermicide, risk factors to be aware of and to avoid? Generally, how safe is spermicide + her on the pill, even if she's not 100% strict with timing?

On a different note - how is it that supranormal levels of testosterone (ex: TRT / steroids) make men infertile? What are long term effects / how reversible is it?

 

[Thomas the Rhymer]

Thomas: thank you for this write-up.

Question on spermicide: could you please advise how effective it is in preventing pregnancy - how it works, effectiveness if woman is not on any other birth control, safety if coming inside her with only spermicide, risk factors to be aware of and to avoid? Generally, how safe is spermicide + her on the pill, even if she's not 100% strict with timing?

On a different note - how is it that supranormal levels of testosterone (ex: TRT / steroids) make men infertile? What are long term effects / how reversible is it?

Spermicide use is associated with an 18% risk of pregnancy, with perfect use, according to the Pearl Index (i.e. if one hundred couples use spermicide as a contraceptive, 18 will fall pregnant). In the real world, it is about 28% effective. It also regularly causes skin and mucosal irritation, which can lead to an increased risk of getting STD's. In medical school, we were basically told to never recommend it due to its low effectiveness and due to the irritation.

Oral Contraceptives, with perfect use, have a failure rate of 0.3%. In the real world, women have an annoying habit of skipping, forgetting, missing doses, so in reality it's more like 9%.

Assuming you are going to use both spermicide and an oral contraceptive, and you are using it imperfectly, then multiplying the probabilities gives a combined failure rate of 2.52%; in other words, of couples using spermicide and oral contraception with poor technique, about 2-3 out of 100 will have a pregnancy. With perfect use (in other words she takes the pill like clockwork and the spermicide is correctly applied according to the manufacturers instructions) the failure rate will be 0.54% (in other words, between 0-1 out of a hundred couples will fall pregnant).

Wikipedia now has an excellent summary table of the effectiveness of all the contraceptives in the following article: http://en.wikipedia.org/wiki/Comparison_of_birth_control_methods

'Doubling-up', in other words using more than one method of contraception (eg. pill + condom) is known to dramatically reduce pregnancy risk. Somewhere else on this forum I remember mentioning that withdrawal + condom is almost as effective as the pill.

With regards to your question on testosterone, I do intend at some point to write a post on male physiology that will clear up that and related questions in detail, but basically testosterone suppresses the release of follicle stimulating hormone from the brain. Follicle stimulating hormone is required to stimulate sperm production, so without that hormone you won't have sperm.

It can take several months for sperm production to properly kick in again once steroids are stopped. In this article of 4 case reports of steroid users, it took between 8 - 20 months to become fertile again:
http://humrep.oxfordjournals.org/content/12/8/1706.full.pdf

It is also possible to speed up the process by replacing Follicle Stimulating Hormone; in this case study, the duration to fertility was shortened to 3 months: http://www.ncbi.nlm.nih.gov/pubmed/7714991

 

[polar]

Thanks Thomas. I understand the multiplied probabilities, thank you for explaining. If I'm understanding you correctly, spermicide is fairly effective if combined with pulling out, but increases the risk of infection due to irritation.

That being said, is it accurate to say that raw dog + no Pill + spermicide + without pulling out is safer than raw + no Pill + pull out?

 

[Thomas the Rhymer]

Thanks Thomas. I understand the multiplied probabilities, thank you for explaining. If I'm understanding you correctly, spermicide is fairly effective if combined with pulling out, but increases the risk of infection due to irritation.

That being said, is it accurate to say that raw dog + no Pill + spermicide + without pulling out is safer than raw + no Pill + pull out?

Withdrawal, with perfect use, has a failure rate of 4%; in the real world, a lot of men don't have adequate self control, leading to a real world failure rate of 18%.

Using spermicide with withdrawal, by multiplying the probabilities we get a range of between 0.72% to 5.22%, so yes, combining spermicide with pulling out will dramatically reduce the chance of making a girl pregnant, especially if you are doing it properly.

 

[JayJuanGee]

Thanks Thomas. I understand the multiplied probabilities, thank you for explaining. If I'm understanding you correctly, spermicide is fairly effective if combined with pulling out, but increases the risk of infection due to irritation.

That being said, is it accurate to say that raw dog + no Pill + spermicide + without pulling out is safer than raw + no Pill + pull out?

Withdrawal, with perfect use, has a failure rate of 4%; in the real world, a lot of men don't have adequate self control, leading to a real world failure rate of 18%.

Using spermicide with withdrawal, by multiplying the probabilities we get a range of between 0.72% to 5.22%, so yes, combining spermicide with pulling out will dramatically reduce the chance of making a girl pregnant, especially if you are doing it properly.

Hi Thomas... Thanks.

I don't necessarily want to belabor the point regarding the withdrawal method, because you seem to have mostly addressed it.

However, what if we presume that guys have perfect control and technique in which they fully and completely pull out before ejaculating. Is the problem and the 4% error rate coming from small quantities of sperm being inside pre-ejaculation fluids or is there some other explanation for how these chicks are getting immaculately pregnant?

 

[Thomas the Rhymer]

Thanks Thomas. I understand the multiplied probabilities, thank you for explaining. If I'm understanding you correctly, spermicide is fairly effective if combined with pulling out, but increases the risk of infection due to irritation.

That being said, is it accurate to say that raw dog + no Pill + spermicide + without pulling out is safer than raw + no Pill + pull out?

Withdrawal, with perfect use, has a failure rate of 4%; in the real world, a lot of men don't have adequate self control, leading to a real world failure rate of 18%.

Using spermicide with withdrawal, by multiplying the probabilities we get a range of between 0.72% to 5.22%, so yes, combining spermicide with pulling out will dramatically reduce the chance of making a girl pregnant, especially if you are doing it properly.

Hi Thomas... Thanks.

I don't necessarily want to belabor the point regarding the withdrawal method, because you seem to have mostly addressed it.

However, what if we presume that guys have perfect control and technique in which they fully and completely pull out before ejaculating. Is the problem and the 4% error rate coming from small quantities of sperm being inside pre-ejaculation fluids or is there some other explanation for how these chicks are getting immaculately pregnant?

That's a great question.

I don't have any good data on this, but I was taught in medical school that the main problem was bad timing, i.e. pulling out after the beginning of ejaculation. The other issue was going back for round 2 without washing and urinating first, which means that sperm are still left behind from round 1.

I looked up the definition of 'perfect use': 'Perfect' use only implies that the couple understand the method, are able to use it correctly and are willing to use it, not that they pulled it off (or in this instance, pulled it out) perfectly at every instance. So if a guy accidentally goes off inside a woman, his use is still 'perfect' provided that he was trying to withdraw and that he knows he was supposed to come out before ejaculation. (Similarly, condom use is considered perfect is the couple know how to put on a condom and put in on for every intercourse - even if the condom bursts, it's still considered 'perfect' use. In reality, a lot of people don't know how to put on a condom correctly or they use it inconsistently.)

The vast majority of withdrawal users are 'imperfect' because guys say they want to withdraw but when it comes down to the moment it feels too good to pull out and they end up not doing it - in other words, they never really intended to withdraw in the first place.

Of note is that withdrawal becomes more effective with experience. It's not a good method to suggest to a young sexually inexperienced teenager, but for a mature guy who has been using the withdrawal method for years it is probably going to be highly effective.