Female age is the most significant factor that affects the success of infertility treatment. As a woman’s age advances, it leads to a drop in the ovarian reserve and a deterioration in egg quality. The rate of fertility decreases with each passing year, particularly after the age of 35, and reaches to its maximum after the age of 40. Eggs obtained from women over 40 often exhibit a high incidence of chromosomal abnormalities. This hinders embryo implantation and significantly increases the risk of miscarriage in resulting pregnancies.

Irregular or abnormal ovulation accounts for approximately 5-25% of the causes of infertility. Under normal circumstances, one of the immature eggs in the ovaries develops, grows, and eventually ruptures, leading to ovulation. The absence of ovulation, known as anovulation, is the main cause of infertility due to menstrual irregularities. Polycystic ovary syndrome (PCOS), hypogonadotropic hypogonadism, and endocrine disorders are examples of conditions in this category. Various tests such as ultrasound (USG) for ovulation tracking, measuring progesterone hormone levels in the blood, examining basal body temperature, or using ovulation kits can determine whether ovulation is occurring.

The uterus is connected to the ovaries through channels referred to as uterine tubes, fallopian tubes, or salpinges. There is one tube on each side of the uterus. The egg released from the ovary is captured by the fringed structures at the end of the tube called fimbria. For pregnancy to occur, sperm deposited in the vagina must pass through the cervical canal and reach the egg in the fallopian tubes. Therefore, it is important to assess whether the tubes are open and functioning properly. Tubal disorders account for approximately 35% of the causes of infertility. Hysterosalpingography (HSG), also known as a uterine X-ray, can detect tube blockages and any resulting damage. If the tubes are found to be closed, damaged, or adhered, they can be surgically corrected. However, if surgery is unsuccessful, in vitro fertilization (IVF) is the preferred treatment option.

Underdevelopment or complete absence of the uterus, the presence of a partition (septum) narrowing the uterine cavity, conditions like double uterus or unicornuate uterus (congenital abnormalities), can prevent couples from conceiving or lead to repeated miscarriages. Additionally, uterine fibroids and polyps that develop later in life can also cause infertility. Previous uterine surgeries, abortions, or infections can result in adhesions within the uterus, causing infertility. These conditions can be diagnosed through ultrasound or hysterosalpingography (uterine X-ray), and can be corrected through hysteroscopic surgery.

Approximately 5-10% of infertile couples have normal test results. Many couples undergo extensive testing to determine the cause of their infertility. However, if no identifiable cause can be found despite all investigations, it is referred to as “unexplained infertility.” In the treatment of unexplained infertility, limited success can be achieved through techniques such as insemination and ovulation induction. However, since the underlying cause is unknown, the chances of success with these treatments are limited. If these treatments have been attempted several times without success, it is advisable to proceed to assisted reproductive technologies such as IVF.