Fertility of the Human Race

The fertility of the human race, compared to other mammals, is not high. When everything is fine with both partners, conception occurs around the middle of the cycle during ovulation, and the chance of pregnancy in one menstrual cycle, i.e., month, is about 20%, which is lower than in other animals where it ranges from 80-90%. What is different in favor of the human race is the fact that we can achieve pregnancy every month, provided that the woman has regular cycles, while in other species this is reserved for mating periods once or multiple times a year. This is why a certain period of unprotected intercourse is required to satisfy the statistical probability of achieving pregnancy. From the study of the physiology of egg cells, we know that after ovulation, the oocyte has a certain duration that is shorter than one day, so the timing of intercourse is crucial. Namely, viable sperm can survive for up to 2 days in the woman's fallopian tubes waiting for the egg to enter after ovulation for fertilization to occur.  Thus, the period when intercourse should take place is just before and during ovulation.

Considering the obligations and dynamics of modern life, among younger couples, i.e., women, it is tolerated to have up to a year of intercourse before consulting specialized institutions dealing with infertility. Realistically, the statistical probability of achieving pregnancy is fulfilled after 6 months of targeted intercourse, and therefore, in couples where the woman's age is over 35, it is advised to seek diagnosis and treatment after 6 months to avoid wasting time.

And this has its physiological reason. Egg cells are formed in every woman while she is still a fetus in the mother's womb, specifically in the 6th month of intrauterine life. They pause in one of the stages of meiotic division, where they remain until the day when, after the establishment of menstruation, they begin to develop in a wave of cells that will go towards ovulation that month. Of the thousands of cells that start, only one will reach ovulation, while the others will perish. The number of egg cells we are born with is finite; they do not divide or multiply after birth, when we have the most. Their number only decreases over time because every day, even before menstruation is established, a certain percentage slowly deteriorates. The ovarian reserve with which we will be born and enter reproductive age depends on many factors, including genetics, various influences on the mother's pregnancy, exposure to radiation, and toxic chemicals in life, etc. When the ovaries reach a reserve of about 37,000-40,000 egg cells, which typically occurs in the average population around the age of 37, new waves of egg cell deterioration begin, which further rapidly decrease the ovarian reserve and lead to menopause, which in our region averages around 47-48 years. If it weren't for this wave of egg cell deterioration, menopause would occur around the age of 70. It is assumed that this is the way our species wanted to protect women from late pregnancies that carry significant health risks, starting from the heart, which during pregnancy must have a minute volume 50% greater than outside of pregnancy, to the kidneys, whose glomerular filtration must increase by 50%, as well as all other organs that, at a time when our health slowly begins to decline, need to operate at an increased capacity.