If sex is infrequent, then it may occur at times when the woman is not ovulating (releasing an egg). Conception can occur in a woman on only five or six days a month, so if sex occurs only once a month, those vital days may be missed. This is actually a quite common cause of apparent infertility in this busy modern society where both potential parents may work, are stressed and over tired. Occasionally, poor sexual technique, with ejaculation near the outside of the vagina, may be a problem.
Rarely, a woman may be allergic to, and develop antibodies against, her partner’s sperm, which are rejected and destroyed by her body. Sperm from another man are not normally affected.
Diseases of the pituitary gland in the brain, hypothyroidism (an underactive thyroid gland in the neck), poorly controlled diabetes mellitus and a deficiency of vital minerals (eg. zinc) may also be responsible for infertility in both sexes.