Causes of female infertility
There are many reasons which are responsible for infertility in women.
Sexually transmitted infections (STIs) are one of the major causes of infertility.
Blockage of the fallopian tube
In women, there are many diseases which cause inflammation of the reproductive tract, resulting in scarring and the sticking together of tissue to create blocks. In this regard, sexually transmitted infections are one of the major causes of infertility. If it is left untreated, gonorrhoea and chlamydia can infect the fallopian tubes, the uterus and ovaries. These can cause pelvic inflammatory disease (PID), which occasionally has no symptoms and so goes unnoticed (silent PID), causing scarring of the fallopian tubes and blocking the egg from travelling down the tubes to meet the sperm. After one episode of PID, a woman has an estimated 15% chance of infertility, while after two episodes the risk rises to 35%, and after three episodes the risk of infertility is nearly 75%.
Harmful traditional practices, like female genital cutting, can cause trauma and infections which lead to infertility.
Similarly, postpartum and post-abortion infection can also cause PID, which may lead to infertility. Additionally, non-sexually transmitted diseases, such as genital tuberculosis, schistosomiasis and endometriosis, and harmful traditional practices like female genital cutting, can cause trauma and infections which lead to infertility.
Ovulation disorders
Ovulation disorders in the hypothalamus-pituitary-ovarian system are associated with an absence of ovulation. For example, when there is a high level of the hormone prolactin, produced by the pituitary gland, it inhibits ovulation (hyper-prolactinaemia). Other factors that can prevent or inhibit ovulation include ovarian tumours, thyroid gland disorder, stress and malnutrition.
Uterine factors
When there is abnormal development of the uterus (congenital malformation), or abnormal growths in the uterus (fibroids), adhesion of the uterus due to infection or abortion can affect the possibility of pregnancy, either by interfering with the transport of male sperm, or with embryo implantation.
Cervical factors
In a few cases, the cervical canal is too narrow and prevents the passage of sperm into the uterus. Hormone imbalances (such as low oestrogen levels) can cause inadequate cervical mucus, or make it so thick that it blocks sperm transport. In rare cases, the cervical mucus and fluids in the vagina may contain chemicals (antibodies) that paralyse or inhibit sperm.
Vaginal factors
In extremely rare cases, conditions like a vaginal septum (a tissue in the vagina developing abnormally in the womb) that inhibits sperm transportation, and even the congenital absence of the vagina, can be causes of infertility. Finally, extreme spasm of the vaginal muscles (vaginismus) during intercourse can prevent penetration of the penis, and so result in infertility.