About nine per cent of couples choose not to have children, and a further 15 per cent cannot do so because of infertility. Couples may choose not to have children for a variety of reasons. Most often it is because neither partner is willing to sacrifice a part of their occupation or career, which is necessary unless their children are to be brought up by a child minder -unacceptable to some people. Sometimes a husband and wife preclude children on other grounds. Couples may decide to remain childless if either has a hereditary condition that may make childbearing dangerous, or may endanger theof their children. A number of married couples believe that the problem of overpopulation prohibits people like themselves from bringing more children into the world.
Childlessness through infertility is, like voluntary childlessness, on the increase in the industrialized countries. Many couples are putting off having children until their late 20s, early 30s or even later: by this time their fertility peak has passed. Sexually transmitted disease, mostly in the form of gonorrhoea, is causing more blocked Fallopian tubes in women as it becomes a worldwide epidemic. Prolonged use of the Pill can cause a slow return to ovulation after a woman has stopped using it. Lastly, exposure to drugs, X-rays, food additives and pollutants is rising, some or all of which may play a part in reducing fertility. In an increasing number of cases infertility can be treatedly. In addition childless couples are often in a position to foster or adopt children.