In normal conception, an egg is released by the ovary and picked up by the patent fallopian tube. The sperm deposited into the vagina swims up into the uterine cavity through the cervical canal, reaches the fallopian tube, where it fertilizes the egg. The fertilized egg (embryo) travels through the tube and enters the uterine cavity, where it attaches to the inner uterine lining (endometrium) by a process called implantation. When implantation occurs, pregnancy ensues. A problem arising at any step in this process of conception may result in infertility.

Infertility is the inability of a couple to achieve conception or to bring a pregnancy to term even after one year of regular unprotected intercourse. Infertility may be primary or secondary infertility. Primary infertility is the condition in which the couple had never conceived before. Secondary infertility is the condition where the couple had a prior pregnancy, although not necessarily a live birth.

The average chance of conception among fertile couples is 10-15% per month. So, over a period of one year, about 80% of normal couples achieve conception.
Approximately 15% have fewer children than they want (subfertile couples), whereas about 10% cannot conceive without assistance (infertile couple). In other words, about 25% couples are below the normal fertility range.

The causes of infertility can be a male factor and/or a female factor abnormality. Sometimes, it may be due to an unexplained cause. Basic evaluation of the couple helps in the diagnosis of the cause for infertility and its contributing factors.