PROCREATION: A COMPLEX PROCESS
What is more essential for a couple than to have a child? Sometimes, an unfulfilled desire…
Fertility varies from one to another and depends on sexual activity: The probability of pregnancy during a menstrual cycle is low, in the range of 20-25% (1). Fertilization, as a prelude to pregnancy, is in fact a complex physiological process that is regulated by multiple factors, including hormonal ones.
(1) – BEH, INVS, N°7-8-9 du 21 février 2012
Fertalization in short
Fertilization is the outcome of the encounter between an ovum and a sperm cell, two reproductive human cells. The most favourable moment to this encounter is before the 13th day of a 28-day cycle, which means at ovulation.
Ovulation: The ovum (egg) develops in the ovary inside the “follicle” then released toward the fallopian tube. This process is carried out under the control of brain hormones (FSH and LH); which are themselves influenced by hormones that are secreted by ovaries.
The “encounter”: It happens within the tube, where sperm cells swim up after their release in the vagina. Sperm cells must be in a sufficient large number, mobile and find a favourable milieu in the cervix, notably the mucus; which quality depends on cerebral and ovarian hormones (estrogens and hCG).
Fertilization itself: Only one of these sperm cells will fertilize the egg. An egg-cell is therefore created, it predetermines the embryo. This cell starts dividing and begins its descents towards the vagina.
Implantation: The future embryo reaches the uterus. It implants within the endometrial which is pre-prepared by ovarian hormone stimulation (estrogens then progesterone).
Every step of this process is crucial and any disruption compromises the future pregnancy.