Causes of Infertility

Definition of infertility: Failure to achieve a clinical pregnancy after 12 months or more of regular unprotected sexual intercourse. One out of six couples on average are suffering from this problem worldwide. The minimum requirements to achieve a pregnancy are ovulation and patent fallopian tubes in the female partner and normal sperm quantity and quality in the male partner. Hence, both male and female factors can contribute to infertility.

Main reasons that lead to infertility:

Female Side:

1) Age

As women age, especially after the age of 35, the chance of chromosome abnormality in the embryo increases, which can lead to high risk of miscarriage and stillbirth. Many women are even facing the problem of premature ovarian failure nowadays.

2) Ovulation

No ovulation or irregular ovulation maybe due to primary or secondary endocrine disorder or high prolactin level. Polycystic ovarian syndrome (PCOS) is a common cause of no ovulation or decreased ovulation among women of childbearing age.

3) Some gynaecological problems can cause structural or functional abnormalities of the genital tract. E.g. uterine abnormality or tubal problem, resulting in infertility or miscarriage.

Past infection including pelvic infection, salpingitis, appendicitis or previous lower abdominal surgery like appendicectomy or tubal ligation can cause tubal damage, adhesion, filled with fluid or total blockage.

For the uterus, there may be endometrial lesions, such as inflammation, adhesions, polyps, uterine fibroid, endometriosis.

Male Side:

1) Sexual dysfunction leading to ejaculation disorders – e.g. psychological factors or prostatitis can cause sexual impotence, premature or delayed ejaculation, reverse ejaculation.

2) Poor semen quality – including azoospermia, oligospermia, immotile sperm, poor sperm morphology, which can be caused by diseases, bad habits such as smoking, alcohol, unfavourable influence of high temperature, drugs, toxins, chemicals, radiation.

Infertility may be caused by both male and female partners, so both sides should be checked.

However, based on currently available investigations, no cause of infertility can be found in 10-20% of infertile couples and this is termed infertility of unknown cause.