For most young people today, the biological ability to reproduce comes about 10 years too early. Most prefer to postpone childbearing until their schooling has been completed and they are somewhat settled in their relationships and careers. Since adolescents and young adults generally become sexually active before this occurs, birth control and fear of pregnancy are frequent concerns. Protecting fertility may be the furthest thing from their minds. But eventually, a majority of couples decide to have children. Of these couples, 10 to 15% will have some sort of fertility problem. Many find it ironic that after years of anxiety over late periods, burst condoms, and missed pills, they may discover that becoming pregnant is not so easy after all.

Infertility in females is the inability to conceive; in males, the inability to produce viable sperm in sufficient quantity. About 40% of fertility problems are due to infertility in the male partner; 50% of the time, the female partner is infertile; and in 10% of the cases the problem is shared or the cause is unknown. Problems with fertility have risen dramatically in recent years. Researchers suspect that several factors have contributed to this rise.

Infections of the reproductive system often have adverse effects on long-term fertility. These infections are primarily sexually transmitted diseases (STDS) such as gonorrhoea, syphilis, chlamydia, and pelvic inflammatory disease (PID). STDs have reached epidemic proportions in North America, especially among adolescents and young adults. A woman's fertility is especially vulnerable, as these infections may cause scarring in the delicate tissue of the Fallopian tubes. Tubes blocked with scar tissue do not allow for the passage of the oocyte or sperm.

Sometimes these infections, especially chlamydia and PID, occur with minor or even no symptoms. By the time they are discovered, damage may already have been done. In order to protect themselves from these infections, women and men are advised to use both condoms and spermicide when having intercourse (unless both are monogamous and uninfected). The condom provides a barrier not only to sperm, but also to bacteria and viruses. The spermicide provides a hostile environment for many pathogens and helps with birth control as well. Men and women should be aware of signs of infection, including exposure to a partner with an STD, pelvic pain, and any unusual discharge. Women should have yearly pelvic exams that include screening for asymptomatic STDS.

Some women experience a loss of the menstrual cycle after they stop taking oral contraceptives, and have difficulty conceiving. Women who had irregular periods before starting on the Pill are most likely to experience this effect. IUDs slightly increase risk of PID.

It has become increasingly common for women to delay childbearing until they are in their thirties and even early forties. (Men can wait even longer.) Many feel that better financial, marital, and job security will improve their potential to be good providers and parents. Others simply have other things they want to do before having children.

Unfortunately, risk of infertility increases with age, especially in females. Each year that goes by is one more year in which physiological barriers to reproduction can arise. Endometriosis is a good example. This disease involves the abnormal growth of the uterine lining, the endometrium. Endometrial cells may grow on the ovaries, or into the Fallopian tubes, which may become blocked. Almost 20% of infertile women have endometriosis, which typically occurs in women in their thirties and forties who have not had children.

Many factors can interfere with the menstrual cycle, especially in younger women. Heavy exercise, low-calorie diets, weight loss, too little body fat, obesity, smoking, alcohol and drug abuse, too much caffeine, and even psychological stress can interrupt ovulation and cause infertility, at least temporarily. Normal cycles often resume once the cause of the problem is discovered and corrected.

A word of caution: An absence of the menstrual bleeding does not necessarily mean a woman is infertile! Many young women erroneously assume they cannot get pregnant since they are not having periods, but it is possible that ovulation is still occurring. Unless the woman is trying to conceive, birth control is essential even in the absence of menstrual periods.

Couples who have not conceived after a year of trying to get pregnant are generally advised to look for a medical diagnosis. Sometimes couples simply need to keep trying; about half of these couples succeed in conceiving even with no treatment. But since infertility treatment can take several years to produce a successful pregnancy, early investigation is recommended, especially for older couples.

Treatment for infertility begins with medical testing to discover why conception has not occurred. The man's sperm is analysed, and the woman's menstrual cycle is evaluated to be sure she is ovulating. Hormone levels are checked, and samples of the uterine lining may be taken. The woman's reproductive organs are evaluated with x-rays and laparoscopy. (A laparoscope is a thin telescope to which a laser is attached. It is used to see the reproductive organs and sometimes treat certain problems.)

Medical testing for infertility can be an arduous process, both physically and psychologically. The process includes embarrassing questions, physical discomfort, financial expense, and months of waiting for test results. Sex can become a scheduled and stressful event, rather than an expression of love and desire. Love, understanding, and mutual support are vital for couples undergoing infertility evaluation to prevent the marital discord and decline in sex drive that sometimes occur in this situation.

About half of all couples undertaking treatment for infertility eventually have biological children. In some cases, the physiological barriers to conception may be corrected with medical procedures. When this cannot be accomplished, several alternatives are available, depending on the nature of the infertility. Donor sperm may be used to fertilise the woman's egg if the man is infertile. When for some reason conception cannot occur in the woman's body, various in vitro fertilisation (IVF) techniques may help. With IVF, an oocyte is fertilised by sperm in the laboratory. The fertilised ovum is then placed back in the uterus to develop. Oocytes and sperm may come from the biological parents or from donors. If a woman cannot produce oocytes, the couple may opt for a surrogate mother, with the man's sperm fertilising the egg of another woman, who carries the child and delivers it to the infertile couple after birth. If the woman can produce oocytes but for some reason cannot have a pregnancy, a second woman may provide a "host uterus" for the fertilised egg from the original couple. Many couples become parents by adopting children.