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Both sterility and infertility are caused by various factors that may affect the woman (female cause), the man (male cause), or both partners (mixed cause).
In a certain percentage of cases, the sterility factor remains undiagnosed (unexplained sterility or sterility of unknown origin).
Age plays a significant role in female fertility.
At birth, women have the maximum number of oocytes (eggs) in their ovaries. This number decreases throughout life, so by around age 50, 80% of women have depleted their ovarian reserve, leading to menopause.
Female fertility remains stable until age 35, but after 38, it declines considerably, along with oocyte quality (increased chromosomal abnormalities that result in embryos with low implantation potential or high miscarriage rates).
Assessing ovarian reserve is crucial for determining the most suitable treatment.
The ovarian cycle is essential for achieving pregnancy.
During the ovarian cycle, ovulation occurs, and the endometrium prepares for embryo implantation. It lasts approximately 28 days (25-30 days in most women), with ovulation occurring around day 14.
Polymenorrhea: Shortened menstrual cycles (less than 21 days).
Oligomenorrhea: Prolonged cycles (over 35 days up to 6 months).
Primary Amenorrhea: Absence of menstruation by age 15.
Secondary Amenorrhea: Absence of menstruation for at least 6 months. Causes include polycystic ovary syndrome (PCOS), eating disorders (anorexia, bulimia), elite athletics, hyperprolactinemia, or genetic conditions.
Anovulation: Failure to release a mature oocyte. Causes include ovarian hormone imbalances (estradiol, progesterone), hypothalamic-pituitary axis dysfunction (GnRH, FSH, LH, prolactin), or thyroid disorders (TSH).
Anovulation accounts for 25% of cases and has a favorable prognosis with proper diagnosis and treatment.
Also known as premature ovarian insufficiency, it involves the cessation of ovarian activity before age 40. It affects approximately 1-4% of women of reproductive age.
Causes include genetic factors (e.g., Turner syndrome, Fragile X syndrome), inherited conditions, enzymatic defects, autoimmune diseases, or chemotherapy/radiotherapy treatments.
Polycystic ovary syndrome (PCOS) is the most common cause of menstrual cycle disorders in women, affecting 4-7% of those of reproductive age. It is defined by the presence of at least two of the following:
PCOS manifests variably, from women with regular periods and normal appearance to severe cases with amenorrhea, hirsutism, acne, and obesity.
A benign condition affecting many women of reproductive age. It involves the growth of endometrial tissue (uterine lining) outside the uterine cavity, commonly in the pelvis (ovaries, fallopian tubes, behind the uterus, intestines, bladder) or, rarely, outside the abdomen.
Although its causes are unclear, endometriosis is associated with sterility in 20% of cases.
Occurs when the fallopian tubes (which transport sperm to the egg and the fertilized embryo to the uterus) are damaged, blocked, or adhered, leading to reduced or absent fertility.
Main causes include infections (gonorrhea, chlamydia), hydrosalpinx (fluid accumulation in the tubes), or endometriosis.
Tubal factors account for 25% of female sterility cases.
Congenital anomalies affecting 5% of the population, often due to abnormal Müllerian duct development during embryogenesis. They may coexist with genital, urinary, or rectal malformations.
The most common types are septate uterus and bicornuate uterus. Uterine fibroids, polyps, or adhesions can also impair endometrial receptivity.
Chromosomal abnormalities in the X chromosome, such as deletions, translocations, or abnormal karyotypes (e.g., Turner syndrome, XO).
Cases where multiple in vitro fertilization (IVF) attempts have failed. Common causes include poor ovarian response, fertilization failure, or embryo implantation failure.
Defined as two or more consecutive spontaneous pregnancy losses before 12 weeks of gestation.
Oligozoospermia: Low sperm concentration, often due to impaired testicular production or partial duct obstruction.
Asthenozoospermia: Reduced sperm motility. Causes include testicular defects, epididymal dysfunction, or chemical/immunological factors.
Teratozoospermia: High percentage of morphologically abnormal sperm, usually due to testicular or genetic issues.
These abnormalities often coexist (oligoasthenoteratozoospermia is the most common diagnosis in infertile men).
Azoospermia: Absence of sperm in semen. Causes include hormonal imbalances (e.g., FSH deficiency), trauma, infections, or genetic disorders (e.g., Klinefelter syndrome). Types:
Absence of ejaculation. Retrograde ejaculation (semen flows into the bladder) may occur due to psychological, neurological, or obstructive causes.
Dilated veins in the scrotum, present in 15-20% of men and 40% of infertile men. It reduces sperm motility and increases DNA fragmentation.
Undescended testicles, affecting 3% of newborns and 30% of preterm infants. Increases the risk of genetic sperm abnormalities.
Difficulty maintaining sexual intercourse, reducing reproductive capacity. Effective treatments (e.g., andrology consultation) are available.
Infections like chlamydia or gonorrhea can transiently impair semen quality by blocking sperm transport.
Y chromosome microdeletions (e.g., AZF region) or chromosomal abnormalities (e.g., Klinefelter syndrome, XXY).
Sterility factors affect both partners, occurring in 20% of cases.
Diagnosed when no cause is identified after thorough evaluation. Affects 10-15% of sterile couples.
Contributing factors include environmental/occupational toxins (lead, pesticides, radiation) and lifestyle habits (diet, smoking, alcohol).
Clínica Girona | Crta. Barcelona 204-206, 2a planta Girona (17005)
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