Natural fertility
Thermal curve - fertility period
Menstrual cycle- hormonal cycle

Tobacco and fertility
Contraception and fertility
Protection of fetus

Hormonal cycle :

In a simple way, the menstrual cycle, which normally lasts 28 days, is regulated by feedback process between hypothalamic-hypophisis axis and ovaries

Menstruation (menses), which is the culmination of a normal cycle without fertilization marks the begginning of a new cycle: by convention the first day of menses is the first day of the cycle

See the same figure with early pregnancy

- Follicular Phase: The first part of the cycle lasts about 14 days ending with ovulation.
During this period the activity of FSH (hormone produced by the hypophysis) tends to gradually decrease while the rate of estradiol (ovarian hormone) augments.
At the end of the follicular phase, the estradiol rate diminishes inducing a peak of production of FSH and LH, an other pituitary hormone, which triggers the ovulatory process.
- Ovulation occurs approximately 38- 40hours after the LH peak.

- Luteal phase : The second phase of the cycle corresponds to the formation and secretion of the corpus luteum.
After the egg evacuation, the ovarian follicle (Graafian follicle) transforms into a new structure, the corpus luteum which secretes an other hormone, the progesterone. Among several actions, the progesterone leads to an increase of the body temperature which only disappears at the end of a cycle without pregnancy

Glossary :
FSH: follicle-stimulating hormone, secreted by the pituitary gland, which is essential to the recruitment and maturation of oocytes (eggs).
LH: luteinizing hormone. LH is involved, among other effects, in triggering the process of ovulation.
Estradiol : steroid hormone, secreted by the follicle: its rate varies depending on the size of the follicle during the cycle.
Progesterone : steroid hormone secreted by the corpus luteum (corpus luteum). This hormone is involved in the lining transformation of the endometrium, which was prepared earlier by estradiol in the first part of the cycle.
Mucosa becomes secretory to facilitate implantation of the embryo.