<span>The reason is that there are a number of processes which are being carried out by the living organisms and they include the application of diffusion. ;)</span>
Ok... This is a bit complicated but bear with me. In a female's body Estrogen and Progesterone are two of the major used to maintain the menstruation cycle. Gonadotrophic substances are an entirely different topic with it being the hormones FSH and LH (These hormones are released while an egg is in development in the ovaries).
Without going into even deeper specifics. Estrogen is used by the body signal to ovulate, as well as thicken the uterine walls... Progesterone is used to maintain the uterine walls "after" the egg is fertilized. What the pill is suppose to do is actually force a premature ovulation, which is why there is estrogen. The Progesterone's job as is maintain the uterine wall's endometrium to a low level and helps keep blood loss from a period at a minimum.
If you need clarification please feel free to question.
Coin flipping simulates the events of mitosis and the production of sperm. This is because females carry XX chromosomes so all eggs will have a singular X chromosome. It is the sperm that determines the sex of the foetus: males have XY chromosomes and therefore sperm will carry either X or Y chromosomes (a 50/50 chance, just like flipping a coin)