Nice topic. Well, for me the intensity of the practise is very connected to my cycle. In the first 2 weeks of my cycle, It’s sparkles, glitter and fireworks. Meditation is deep and there is a lot of ecstatic conductivity. Because of this I always welcome my menstruation 
. However, I overload a lot faster during this time.
In the last 2 weeks of my cycle (starting from ovulation) practise becomes increasingly “boring” (less ‘scenergy’). A bonus is that there is a lot less risk on overload, so when I introduce new practices I try to do it during this time.
I think traditionally spiritual practices for women during menses where discouraged because a lot of practices are geared towards getting energy to flow upward instead of down. Of course, a whole lot of paternalistic and ritualistic nonsense got mixed into it, which created stories of being ‘unclean’ etc. After practising AYP for a while I got so good at playing with this energy that I could start or stop menses at will. I found out however, that obstructing the natural downward flow can create a problem or two. Not recommended!
I don’t do inversions, or mudra’s, bandha’s and postures that create pressure on the lower abdomen (trust me, you don’t want that uterus going into a 3 hour cramp 
). I also tone down practises that strongly pull up the energy (like YMK) to the extend that they don’t interfere with the downward flow too much. Hope this helps!
The semen cycle of men shall be 33 days. I don’t know how long the semen in AYP needs till it reaches the top of the head as ojas as the natural outlet of yang and male energy or residual materials like menstrual blood.
The egg cycle of women is like the moon cycle 28 days. Aristoteles knew of the necessary role of the egg selecting in new research precisely which semen is allowed to enter blocking the others. It is not the merely passive matter to be formed by the semen by Albertus Magus acknowledges that matter has as the formless has the power to urge mind into a form.
But church not liking in the beginning Aristoteles till the more advanced Arabs brought him back said, that the whole man is in the semen as a homunculus also for the alchemists breeding it in their glasses.They divided also not in heaven and earth but heaven and hell below your feet. So downgoing menstrual blood is evil.
But if the return to god on the head by the semen is natural why not egg and menstrual blood to the ground? Taoism and tibetan healing working with earth’s hot magma accepts fully the earth and yin energy and its opposition of heaven and yang though the result shall be a yang body. But they also have yin body practises.
But I Ging 5 fears female nonobidient tricky energies to be tricked out like Odysseus or persuaded by god in Plato’s Timaios.
Axel
My impression is that NFP more accurately defines the fertile time. Here is a link: http://erin-dorr.suite101.com/natural-family-planning-vs-the-rhthym-method-a61339
From what I have heard it is VERY effective, BUT you have to obey the calendar perfectly.
However, we only used this briefly before realizing that I probably am not fertile anyway and my partner had help from my teacher in fine-tuning his tantric control.
Victor you are right, it takes LOTS of trust and faith in the man’s tantric abilities as well as his dedication/motivation! I would not do this lightly; my partner and I have been together 7 years. Without that kind of trust it would be impossible.
thank you dear Radharani 
I just think I should add that different women have different experiences with the pill, though I understand that in general, not adding chemicals/hormones to your system unnecessarily is better.
I had a girlfriend for whom the pill made her depressed and killed her sex drive. We switched to condoms. I had another girlfriend who started the pill when she was not sexually active and had no plans to become so–simply because she had very heavy periods which tended to trigger migraine headaches and the pill helped with both.
My current girlfriend was on the pill before I met her and has been so for years, seemingly suffering no ill effects. I’ve actually encouraged her previously to get off it if she wants, since I use the holdback and blocking methods and wear a condom when I can’t “hold back” any more, but she just wants to be extra-super certain that she doesn’t get pregnant before she’s ready to, so I respect that.
Anyway, so yeah, while natural tends to be best, don’t forget that the pill affects different women differently.
very true!
A question of the women cycle and meditative tantra how pregnancy enters the cycle.
I think as the semen needs to swim to the egg in hard competition with other semen the pregnancy takes place some time after intercourse or an artificial insemination with own or bought sperm of others. How long does it needs till one knows that pregnancy took place. Also a question of pregnancy tests.
But some pretend that they immediately felt and knew that the shot and semen caused pregnancy perhaps even before the arrival of the semen in the egg.
That intercourse may lead to high grades of concentration and sensitivity is no question especially in the case of good meditators and tantrica.
Tibetan take 1o month and not nine for birth. Why? One month before the meeting of egg and semen which becomes valid with the nidation in the uterus the energies of father and mother meet already allowing a spiritual fetus karmically drawn to them or voluntarily chosen by a reincarnating Tulku or buddha to enter these energies. These energies are ida and pingala - the tibetan names not a hand knotted at one’s heart and unknotted in higher spiritual developments for higher bodies.
Their original puts it a little bit otherwise: The spiritual fetus seeing his future parents gets heavily drawn in love to one parent. If its the mother it becomes a boy otherwise a girl.
But also this puts the question, if the pregnancy took already place by the intercourse it was the spiritual fetus who already entered causing such feeling.
Normally women report such feelings of pregnancy already during intercourse But men with a good feel into the body of the partner should have it also.There are so many channels connected between the partners that also the shot of semen is more as a simple deposit in the uterus. The shot can go further on till into the brain e.g.
Axel