1. The biological clock
We tend to forget it, but the main factor limiting fertility remains maternal age. According to experts, women who want to have a child must think about motherhood before 35 if they don’t want to know the pangs of infertility. The number of eggs we have at birth (our ovarian reserves) is dropping at a much faster rate than we think: female fertility is at its peak at 20, at 30, a woman does not have more than 12% of her eggs … and only has 3% at the age of 40.
2. Ovarian disorders
The most common causes of female infertility are the absence of ovulation (this is called anovulation) or ovulation disorders (dysovulation). These disorders of ovarian origin result in the absence of production of fertilizable oocytes. The doctor often evokes this diagnosis in front of absent or irregular periods. This may be due to:
• Polycystic ovary syndrome, which affects between 5 and 10% of women of childbearing age and is characterized by the development of multiple cysts on the ovaries, causing irregular cycles.
• Ovarian failure which affects 1% of women and is characterized by a total absence of ovulation, most often permanent.
3. Hormonal disorders
Prolactin is a hormone secreted by the pituitary gland (located at the base of the brain) and which is believed to rise during pregnancy to participate in the development of the mammary gland. But when there is excess prolactin outside of pregnancy (this is called hyperprolactinemia), this causes a decrease in fertility by dysovulation. The cycles are spaced every two months or stop altogether.
Taking certain drugs (neuroleptics, morphine, estrogens) is often responsible for this hormonal disorder. But it can also be due to certain diseases like chronic renal failure , hypothyroidism or a pituitary adenoma (pituitary gland tumor).
4. Endometriosis
Endometriosis affects at least one in 7 women of childbearing age. This debilitating disease is characterized by the abnormal presence of endometrium (the lining of the uterus) in the ovaries, tubes and outside the uterine cavity. Besides the pain it causes with each cycle, endometriosis causes infertility in 30 to 40% of women who suffer from it.
5. Morphological abnormalities
• The uterine cavity being the place of implantation of the embryo, when the uterus presents a malformation (uterine partition, synechiae or scar bands), this can hamper this implantation.
• An abnormality of the cervix (due to an infection or to a previous treatment of lesions of the cervix) can also prevent the secretion of cervical mucus while it is this which has the power to “boost” the sperm. providing them with the energy they need to get to the egg.
• A fibroid of the uterus (also called myoma) can also interfere with the implantation of a possible embryo.
6. Sexually transmitted infections
Some STIs that are not treated early enough, especially chlamydia infections, can leave marks on the tubes or cause endometritis (infection of the uterine wall) and prevent the proper implantation of an embryo.
More informations : The great fertility book. The practical guide to Medically Assisted Procreation (MAP) and other treatments. Editions Eyrolles
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