Natural fertilization, the female reproductive cycle (ovarian + menstrual). What happens in general

Each month, the reproductive system of a woman of childbearing age undergoes a series of changes known as reproductive cycle. These modifications actually refer to two distinct cycles, which we overlap for convenience: the ovarian cycle, which leads to the release of a mature oocyte from the ovary and the period, relating to the alterations that occur in the endometrium to prepare the woman's body for a possible pregnancy. The term menstrual cycle is often used to actually mean the ovarian one.

Let's see, in summary, what happens during the month:

• Un ovocite matures within a follicle in the ovary;
• The mature oocyte is released duringovulation, which occurs approximately in the middle of the cycle (by convention, the cycle is started on the first day of menstruation);
• The oocyte expelled from the ovary is pushed into the fallopian tubes towards the uterus;
• Parallel to the development of the ovum, the inner lining of the uterus - theendometrium - prepares to receive an eventual embryo and to nourish him;
• If fertilization has actually taken place, the embryo nestles in the endometrium (implant) and pregnancy begins. If, on the other hand, fertilization does not take place, the endometrium flakes off and the tissue fragments are expelled through the process called menstruation, which is the emission of blood, endometrial cells and mucus from the vagina.

Read also: Ovulation calendar

Menstrual cycle, how long it lasts

The duration of the menstrual cycle is calculated from the first day of menstrual bleeding until the day this occurs again. It is usually equal to 28 days, including 4-5 days of menstrual bleeding, but it can vary a lot from woman to woman (cycles of 23 or 35 days are considered normal).

This variability generally refers to the first half of the cycle; the second half has, in fact, a mostly fixed duration, 14 days, from the moment of ovulation.

Read also: Menstrual cycle, get to know it

Fertility, how natural fertilization works

For a complete guide to natural fertilization, from the anatomy of the systems involved, to the menstrual cycle, to the implantation of the embryo, go to the main article

Consultation by Prof Carlo Flamigni, surgeon, freelance professor in the obstetrics and gynecology clinic, member of the National Bioethics Committee

Updated on 02.02.2022

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• fertility
• ovulation
• period