Infertility affects 1 in 10 couples who want children.  Fertility declines in both sexes after the ages of 30-35, and because more and more couples are delaying starting a family until their 30s, infertility is becoming more common in the developed world.  If conception has not occurred after a year of unprotected, regular sex, one or both partners may be having a fertility problem.

Female infertility: 
About half of couples who experience difficulties conceiving do so as a result of female infertility.  Fertility in women decreases with age and is generally lower by age 35, making conception more difficult for women over this age.

 For conception to occur, all of the following steps must take place: ovulation (the    production and release of a mature egg by an ovary), fertilization of the egg by a sperm, transport of the fertilized egg along the fallopian tube to the uterus, and implantation of the fertilized egg in the lining of the uterus.  If any stage is interrupted or does not occur, conception cannot take place.

 What are the causes?
There are a number of fertility problems in females that may affect one or more of the processes required for conception.  The problems can develop at different stages of conception.
   
Problems with ovulation:
A common cause of female infertility   is the ovaries’ failure to release a mature egg during every monthly cycle.  Ovulation is controlled by a complex interaction of hormones produced by the hypothalamus (an area of the brain), the pituitary and thyroid glands, and the ovaries.  A common and treatable cause of female infertility is polycystic ovary syndrome which may cause a hormone imbalance that prevents ovulation from taking place.  Disorders of the thyroid gland, such as hypothyroidism, may also cause a hormonal imbalance that can affect the frequency of ovulation.  Pituitary gland disorders, such as prolactinoma, a non cancerous tumor, may cause a similar imbalance.  In some women, ovulation does not always occur, for reasons that are unclear.  In some cases, women who have been using oral contraceptives for a number of years may take time to reestablish a normal hormonal cycle after discontinuing them.  Excessive exercise, stress and obesity or low body weight may affect hormone levels and cause temporary infertility.

Premature menopause also results in a failure to ovulate.  It can occur with no apparent cause or may be the result of surgery, chemotherapy or radiation therapy.  In rare cases, the ovaries do not develop normally due to a chromosomal abnormality, such as Turner syndrome.

Problems with egg transport and fertilization:
The passage of the egg from the ovary to the uterus may be impeded by damage to one of the fallopian tubes.  This damage may be due to pelvic infection, which may in turn result from a sexually transmitted disease such as chlamydial cervicitis.  Such infections may exist with no symptoms and may be detected only if you have difficulty conceiving.

Endometriosis, a condition that can lead to the formation of scar tissue and cysts within the pelvis, may also damage the fallopian tubes, preventing the passage of an egg.

In some women, the egg cannot be fertilized because the mucus produced naturally by the cervix contains antibodies that destroy the partner’s sperm before they reach the egg.

Problems with implantation:
If the lining of the uterus has been damaged by an infection, such as gonorrhea, the implantation of a fertilized egg may not be possible.  Hormonal problems may also result in the uterine lining not being adequately prepared for successful implantation.  Non cancerous tumors that distort the uterus and rarely, structural abnormalities present from birth may make it impossible for a fertilized egg to embed itself in the uterine lining.

What might be done?
Your doctor will ask you about your general state of health, your lifestyle, you’re medical and menstrual history, and your sex life before recommending particular tests and treatments.

Most causes of female infertility can now be identified through testing.  You can   find   out if and   when you ovulate by using an ovulation prediction kit, available over the counter, or by recording your body temperature daily.  If your doctor suspects that you are not ovulating regularly, you may have repeated blood tests during your menstrual cycle to assess the level of the hormone progesterone (which normally rises after ovulation).Repeated ultrasound scanning of the ovaries during the cycle may also be done to check if and when ovulation occurs.  In addition, a tissue sample may be taken from the uterus and examined for abnormalities. 

If tests show that you are not ovulating, you may need further blood tests to    check the levels of thyroid hormones and other hormones, and drugs may be prescribed to stimulate ovulation. However, if you are ovulating, the next step is to find out whether your partner is producing sufficient normal sperm by analyzing two or more semen samples.

 If you are ovulating normally and your partner’s sperm are normal, your doctor will check if there is a problem preventing the egg and sperm from meeting. For example, you and your partner may be asked to have sex during the time that you are ovulating so that a sample of your cervical mucus (collected within a few hours of intercourse) can be tested for antibodies to sperm.  If analysis of the sample shows antibodies to sperm, there are several methods of treatment.  Corticosteroids may be prescribed to suppress the production of antibodies, or your partner’s semen may be injected directly into your uterus to avoid contact with the mucus.  If these steps are not successful, your doctor may recommend assisted conception.

If the cause of the infertility has still not been found, your doctor may arrange for further investigations to look for a blockage in the fallopian tubes or an abnormality of the uterus.  One such test is laparoscopy, in which an endoscope containing a camera is inserted through the abdomen. Another is hysterosalpingography, in which a dye is injected through the cervix and X-rays are taken as the dye enters the reproductive organs.  The treatment depends on the problem.  For example, a tubal blockage may be corrected by microsurgery, and endometriosis may be treated with drugs.

What is the prognosis?
Treatments for female infertility have greatly increased the chance of   pregnancy.  Success rates vary, depending on the cause of the infertility and the type of the treatment.  Fertility drugs stimulate ovulation in 1 in 3 women, but there is a risk of multiple pregnancies.  Microsurgery to clear obstructed fallopian tubes is sometimes successful but increases the risk of ectopic pregnancy.  Success rates for assisted conception methods range from 15 to 30 percent per individual treatment.

MALE INFERTILITY: In about 1 in 3 couples who have difficulty conceiving, the problem results from male infertility.  In males, fertility depends partly on the production of enough normal sperm to make it likely that one will fertilize an egg and partly on the ability to deliver the sperm into the vagina during sexual intercourse. If either of these factors is adversely affected, infertility may result.

What are the causes?
Unlike the causes of female infertility, which are more easily identifiable, the cause of infertility can be difficult to find in some men.  A cause is discovered in only 1 in 3 men investigated.

Problems with sperm production:
A low sperm count or the production of abnormal sperm may have various causes.  Normally, the testis has a temperature of about 4 degree F (2 degree C) lower than the rest of the body. Any factors that raise the temperature of the testis can reduce the number of sperm produced.
Aspects of your lifestyle that may impair sperm production include smoking, drinking alcohol, using   certain medications and recreational drugs, and even wearing tight clothing.
Sperm production can be adversely affected by some long-term illness, such as chronic kidney failure   and by some infections, such as mumps, that occur after puberty.  Conditions affecting the urethra, such as hypospadias, or the scrotum, such as a varicocele, may also reduce fertility.  In addition, fertility problems may occur if the testis is damaged by medical procedures such as surgery, chemotherapy, or radiation therapy for disorders such as cancer of the testis.

 Low sperm production may also be due to a hormonal or chromosomal deficiency.  Insufficient production of the sex hormone testosterone by the testes can cause a low sperm count. Since the pituitary gland controls testosterone secretion, pituitary disorders, such as a tumor, may also lead to reduced sperm production.  Rarely, low testosterone levels are due to a chromosomal abnormality such as K line felter syndrome.  The most common cause of a low sperm count is idiopathic oligospermia, in which there is a reduced sperm count for no identifiable reason. There is no effective treatment.

 Problems with sperm delivery:
A number of factors may prevent sperm from reaching the vagina.  The most easily identifiable factor is impotence - the inability to achieve or maintain an erection.  Other factors include damage to the Epididymis and vas deferens (tubes that transport sperm).Damage is often due to a sexually transmitted disease such as gonorrhea.  It may also be caused by retrograde ejaculation, in which semen flows back into the bladder when the bladder valves do not close properly.  This condition can occur after prostate surgery.

What might be done?
Your doctor will ask about your health, medical history, and sex life and give you a physical examination, including an examination of your genitals.  You may also need to provide semen samples.  If your sperm count is low or your sperm are abnormal, further investigations will be done, such as blood tests to check hormone levels.  Treatment depends on the diagnosis.  Low testosterone levels can be treated with hormone injections.  Artificial insemination may be used in cases of impotence or retrograde ejaculation; for the latter, the sperm may be taken from urine.  Damage to the epididymis or vas deferens may be treated by microsurgery.

If you produce only a few healthy sperm, a sample may be taken from an epididymis or testis by microsurgery.  A process called intracytoplasmic sperm injection (ICSI) may then be used to fertilize an egg with a single sperm.

What is the prognosis?
 If the infertility is treatable, the chance of regaining fertility is high.  With artificial insemination the chance of conceiving in one menstrual cycle is about 10-15 percent, and the treatment usually works within 6 months.  Each attempt at assisted conception is successful in 15-30 percent of cases, depending on the technique.