Based on the characteristics of a menstrual cycle, the days of fertility can be determined quite accurately. A regular female cycle generally lasts for 28 days, of which the first 3-5 days are the days of menstruation. Egg maturation occurs around the 14th day of the cycle, and the egg can await insemination for even two days. Sperms are viable for a couple of days after sexual intercourse. This is why pregnancy can develop from sexual intercourse a couple of days before or after egg maturation. Some women achieve pregnancy very rapidly and easily, while others need more time to reach the conceiving of a child. Other women may long for the natural achievement of pregnancy in vain, due to a known cause, or even when no anatomical, physiological or other irregularities are revealed.
Inability, or infertility is when after 12 months of regular sexual intercourse around the time of ovulation, with 2-3 occasions a week, the intended pregnancy is not achieved. Infertility affects 10-15% of couples. The number of childless couples has increased steadily in the past decades, among others, due to the continuous latening of the age, when women undertake pregnancy, and also due to the gradual decay of productiveness within the population. The chance of becoming pregnant gradually decreases from the end of the thirties, the decay of productiveness accelerates, and over the age of forty, the chance of a successful pregnancy is minimal. However, one must differentiate between infertility and sterility. Sterility, absolute reproductive inability is when either one of the couple has such a definitive, permanent cause, due to which conception/achievement of pregnancy is impossible. Certain developmental defects, conditions produced by surgical interventions, high degree loss or total absence and disorder of gametes. Infertility is when less or moderately severe causes make the achievement of pregnancy difficult, or when achieved pregnancy repeatedly miscarries at an early stage of the pregnancy.
In case of sterility, the use of a donated egg and sperm is also possible. In case of infertility, there is a possibility for insemination or in vitro fertilization, depending on the given problem. In the latter case, a number of laboratory techniques are applied to promote egg fertilization and achievement of the intended pregnancy.