Infertility is the inability to conceive or produce children in spite of unprotected sexul cohabitation. The term infertility is not synonym of sterility which means complete inability to produce children.
Reason of Infertility: There are a number of causes of infertility in the human beings. These can be categorized as physical, congenital, drugs, immunological and psychological.

Infertility In Males: A fertile male deposite about 3 - 4 ml semen per ejaculation containing over 200 million normal, motile sperm. A male human is infertile if the semen has low sperm count or abnormal sperm structure or poor sperm motility. The causes of male infertility may mclude Cryptorchidism (Failure of testes to descend into scrotum), hyperthermia (higher temperature in scrotal sac due to tight undergarments), blockage of vas deferens, alcoholism which inhibits spermatogenesis), infection with mumps virus after puberty, deficiency of genadotropin, ejaculation defect, exposure to radiation etc.

Infertility in Female: In females infertility may be due to irregular ovulation or no ovulation or defect in the genital tract like impared motility of fallopian tube, defective uterine endometrium, defect in the cervix, defective vaginal of deficiency of sex hormones.