This is the simplest form of assisted conception treatment. It involves inserting sperm into the wife's uterus at the time of ovulation. The sperm sample is first prepared to remove dead and weak sperm and the best sperm are then strengthened even further to improve their ability to make a baby. The wife too is usually given hormonal medications (tablets and occasionally hormonal injections) so that she will produce more eggs from her ovaries. This combination of good sperm, extra eggs and timing during ovulation is the key to success. IUI is useful for couples with unexplained infertility and where the partner's sperm is slightly below normal. It cannot be used where the fallopian tubes are damaged or where the sperm is very poor.