Damage to the fallopian tubes (which carry the eggs from the ovaries to the uterus) can prevent contact between the egg and sperm. Pelvic infections, endometriosis, and pelvic surgeries may lead to scar formation and fallopian tube damage.
Ovulation is affected in some women due to hormonal abnormality. Synchronized hormonal changes leading to the release of an egg from the ovary and the thickening of the endometrium (lining of the uterus) in preparation for the fertilized egg do not occur, in such scenarios.
In some women cervical condition is such that the sperm cannot pass through the cervical canal. Causes of this can be either due to abnormal mucus production or a prior cervical procedure. This problem is treated with Intrauterine Inseminations (IUI).
Abnormal anatomy of the uterus such as the presence of polyps,fibroids or uterine septum can lead to infertility.
In a small proportion of women, the cause of infertility cannot be determined. This is called unexplained infertility.