Causes of Infertılıty
The definition of infertility is the inability of a couple to achieve pregnancy despite a year of unprotected intercourse. If the age of the expectant mother is over 35, 6 months of unprotected intercourse is sufficient for the diagnosis of infertility. Approximately 85% of couples have an identifiable cause of infertility.
The most common causes of infertility are ovulatory dysfunction (lack of regular ovulation), male factor and a disease involving the tubes. The reason for infertility of the remaining 15% of couples cannot be fully revealed. Environmental factors, living conditions, smoking and obesity are the reasons that make it difficult to conceive.
Ovulatory dysfunction is responsible for 25% of infertility and 70% of women with ovulatory dysfunction have polycystic ovary syndrome.
Infertility can sometimes be a result of a related chronic disease (such as hypothyroidism).
Generally, women who have regular periods and experience premenstrual symptoms (such as breast tenderness, pubic cramps...) can be considered to have regular ovulation.
Factors that cause problems in ovulation are thyroid hormone disorders, hyperprolactinaemia (excessive secretion of milk homone), polycystic ovary syndrome and hypothalamic amenorrhoea (less than normal secretion of ovulation hormones from the brain).
Non-ovulation (anovulation) usually occurs in women with irregular periods. This should be suspected if menstrual periods are shorter than 21 days and longer than 35 days. Regular periods do not necessarily mean that ovulation is also present. In most women with ovulation problems, menstrual periods are longer than 25 days. Ovulation usually occurs 14 days before menstruation begins. Obesity alone is a cause of anovulation. A body mass index higher than 27 significantly increases the likelihood of anovulation.
Other causes of anovulation are thyroid diseases (2-3%), pituitary disorders (13% such as hyperprolactinaemia), conditions that increase male hormones such as adrenal hyperplasia or adrenal tumours, unexplained anovulation, 7-8% (inability to ovulate) and functional hypothalamic amenorrhoea (very low body weight, nutritional disorders and vigorous exercise). Infertility is 3 times more common in patients with malnutrition than in those with regular nutrition.
Tubal Factor Infertility
Tubal factor infertility may be due to the obstruction of the tubes or inability of the tube to hold the egg due to adhesions in the abdomen.
Tubal factor infertility should be suspected in women with a history of sexually transmitted diseases, onset of cervical cancer, abdominal surgery or ruptured appendicitis. Hysterosalpingography (HSG) is the most important imaging method that is used to assess the condition of the tubes.
Endometrial (inner lining of the uterus) tissue is also present outside the uterus. 25-40% of female infertility is due to endometriosis. It can cause infertility by changing the intra-abdominal anatomy, disrupting the integrity of the tube or forming cysts (chocolate cysts) in the ovaries. Apart from the mechanical problems it creates, it also impairs egg quality and prevents the fimbrial end of the tube from capturing the egg.
It is not clear if it impairs the receptivity of the uterine wall (endometrial receptivity). Although laparoscopic surgery is known to increase the rate of spontaneous pregnancies, surgery is not recommended for patients who do not have symptoms of endometriosis.
Decreased Ovarian Reserve
As a woman gets older, the number and quality of eggs decreases. Other conditions that decrease ovarian reserve are ovarian surgery, chemotherapy, radiotherapy, family history of early menopause, fragile X premutation (FMR1). Ovarian reserve is determined by AMH (anti-mullerian hormone) test and counting the antral follicles in the ovaries by ultrasound. AMH is secreted from fluid-filled egg-containing sacs called antral follicles in the ovaries. As the number of eggs in the ovaries decreases, the FSH hormone secreted from the brain increases.
Uterine and Cervical Factors (Causes originating from the uterus and cervix)
Intrauterine (uterine cavity) abnormalities lead to poor pregnancy outcomes such as miscarriage and premature birth.
Endometrial polyps, fibroids, intrauterine adhesions and congenital uterine malformations (such as intrauterine curtain) can cause infertility by disrupting the intrauterine structure. These pathologies can be identified with imaging methods such as Sonohysterography (SHG), transvaginal ultrasound and HSG (Hysterosalpingography). In anomalies such as bicornuate uterus, differential diagnosis can be made by using pelvic MRI.
Elimination of these problems with surgery increases pregnancy rates. Infertility caused by cervical problems occurs due to postoperative wounds or decreased mucus secretion. Congenital anomalies of the cervix are very rare.