Infertility is the failure of a couple to conceive a pregnancy after trying to do so for at least one full year. In primary infertility, pregnancy has never occurred. In secondary infertility, one or both members of the couple have previously conceived, but are unable to conceive again after a full year of trying.
Approximately 20% of couples struggle with infertility at any given time. Infertility has increased as a problem over the last 30 years. Some studies blame this increase on social phenomena, including the tendency for marriage and starting a family to occur at a later age. For women, fertility decreases with increasing age:
- Infertility in married women ages 16–20 = 4.5%.
- Infertility in married women ages 35–40 = 31.8%.
- Infertility in married women over the age of 40 = 70%.
Presently, individuals often have several sexual partners before they marry and try to have children. This increase in numbers of sexual partners has led to an increase in sexually transmitted diseases. Scarring from these infections, especially from pelvic inflammatory disease (infection of the female reproductive organs) seems to be in part responsible for the rise in infertility. Furthermore, use of some forms of the contraceptive called the intrauterine device (IUD) has contributed to an increased rate of pelvic inflammatory disease, with subsequent scarring. A study in 2001 found that copper IUDs have probably been wrongfully blamed for tubal infertility, while infection from the sexually transmitted disease chlamydia was likely the cause.
To understand the causes of infertility, it is first necessary to understand the basics of human reproduction. Fertilization occurs when a sperm from the male merges with an egg (ovum) from the female, creating a zygote that contains genetic material (DNA) from both the father and the mother. If pregnancy is then established, the zygote will develop into an embryo, then a fetus, and ultimately, if all goes well, a baby will be born.
Sperm are small cells that carry the father's genetic material. The sperm are mixed into a fluid called semen, which is discharged from the penis during sexual intercourse. The whiplike tail of the sperm allows the sperm to swim up the female reproductive tract, in search of an egg.
The ovum is the cell that carries the mother's genetic material. Once a month, a single mature ovum is produced, and leaves the ovary in a process called ovulation. This ovum enters a tube leading to the uterus (the fallopian tube) where fertilization occurs.
When fertilization occurs, the resulting cell (which now contains genetic material from both the mother and the father) is called the zygote. This single cell will divide into multiple cells and the resulting cluster of cells (called a blastocyst) moves into the womb (uterus). The uterine lining (endometrium) has been preparing itself to receive a pregnancy by growing thicker. If the blastocyst successfully attaches itself to the wall of the uterus, then pregnancy has been achieved.
Causes & symptoms
Unlike most medical problems, infertility is an issue requiring the careful evaluation of two separate individuals, as well as an evaluation of their interactions with each other. In about 3–4% of couples, no cause for their infertility will be discovered. About 40% of the time, infertility
The main factors involved in causing infertility include:
- male problems: 35%
- ovulation problems: 20%
- tubal problems: 20%
- endometriosis: 10%
- cervical factors: 5%
Male infertility can be caused by a number of different characteristics of the sperm. To check for these characteristics, a sample of semen is obtained and examined under the microscope (semen analysis). Four basic characteristics are usually evaluated:
- Sperm count refers to the number of sperm present in a semen sample. The normal number of sperm present in just 1 ml of semen is over 20 million. A man with only 5–20 million sperm is considered subfertile and a man with fewer than 5 million sperm is considered infertile.
- Sperm are also examined to see how well they swim (sperm motility) and to be sure that most have normal structure.
- Not all sperm within a specimen of semen will be perfectly normal. Some may be immature, and some may have abnormalities of the head or tail. A normal semen sample will contain no more than 25% abnormal forms of sperm.
- Volume of the semen sample is important. An abnormal amount of semen could affect the ability of the sperm to successfully fertilize an ovum.
Any number of conditions result in abnormal findings in the semen analysis. Men can be born with testicles that have not descended properly from the abdominal cavity (where testicles develop originally) into the scrotal sac, or may be born with only one instead of the normal two testicles. Testicle size can be smaller than normal. Past infection (including mumps) can affect testicular function, as can a past injury. The presence of abnormally large veins (varicocele) in the testicles can increase testicular temperature, which decreases sperm count. History of having been exposed to various toxins, drug use, excess alcohol use, use of anabolic steroids, certain medications, diabetes, thyroid problems, or other endocrine disturbances can have direct effects on the formation of sperm (spermatogenesis). A study published in late 2001 linked certain organic solvents that men encounter in the workplace as possible causes of low sperm count. The types of solvents are most likely encountered in such occupations as those of professional printers, painters, and decorators. Theories suggest solvents like glycol ethers, which are know to affect animals' reproductive systems, are the most harmful.
Problems with the male anatomy can cause sperm to be ejaculated not out of the penis, but into the bladder; and scarring from past infections can interfere with ejaculation.
Studies continue to uncover reasons for male infertility. In 2001, researchers reported that a certain protein lacking in the sperm could prevent formation of the structure on the head of the sperm that contains enzymes that help penetrate the egg, allowing conception. The finding should lead to further study of the molecular basis of male fertility.
The first step in diagnosing ovulatory problems is to make sure that an ovum is being produced each month. A woman's morning body temperature is slightly higher around the time of ovulation. A woman can measure and record her temperatures daily and a chart can be drawn to show whether or not ovulation has occurred. Luteinizing hormone (LH) is released just before ovulation. A simple urine test can be done to check if LH has been released around the time that ovulation is expected.
Pelvic adhesions & endometriosis
Pelvic adhesions cause infertility by blocking the fallopian tubes and preventing the sperm from reaching the egg. Pelvic adhesions are fibrous scars. These scars can be the result of past infections, such as pelvic inflammatory disease, or infections following abortions or prior births. Previous abdominal surgeries can also leave behind scarring.
Endometriosis is the abnormal location of uterine tissue outside of the uterus. When uterine tissue is planted elsewhere in the pelvis, it still bleeds on a monthly basis with the start of the normal menstrual period. This leads to irritation within the pelvis around the site of this abnormal tissue and bleeding, and may cause scarring. Endometriosis may lead to pelvic adhesions.
A hysterosalpingogram (HSG) can show if the fallopian tubes are blocked. This is an x-ray exam that tests whether dye material can travel through the patient's fallopian tubes. Scarring also can be diagnosed by examining the pelvic area through the use of a laparoscope that is inserted into the abdomen through a tiny incision made near the navel.
The cervix is the opening from the vagina into the uterus through which the sperm must pass. Mucus produced by the cervix helps to transport the sperm into the uterus. Injury to the cervix or scarring of the cervix after surgery or infection can result in a smaller than normal cervical opening, making it difficult for the sperm to enter. Injury or infection can also decrease the number of glands in the cervix, leading to a smaller amount of cervical mucus. In other situations, the mucus produced is the wrong consistency (perhaps too thick) to allow sperm to travel through. In addition, some women produce antibodies (immune cells) that are specifically directed to identify sperm as foreign invaders and to kill them.
Cervical mucus can be examined under a microscope to diagnose whether cervical factors are contributing to infertility. The interaction of a live sperm sample from the male partner and a sample of cervical mucus from the female partner can also be examined. This procedure is called a post-coital test.
Conventional treatment for infertility usually involves invasive and, expensive procedures. There are many alternative treatments available that can increase the chance of conception. Some have been proven effective in clinical studies.
General measures to increase fertility include monitoring ovulation and timing intercourse (optimal chance for conception is within six days prior to and including the day of ovulation); and quitting smoking, excessive drinking, and drug use. To improve sperm quality, men can wear boxer shorts instead of briefs.
Both men and women can increase fertility by eating a well-balanced diet. Good food choices include legumes (especially soy), dark-colored vegetables, fruits, seeds, nuts, and sufficient good quality protein including meat, fish, and eggs. Some people think that refined sugar, processed cheeses, foods made with white flour, and chemical preservatives should be avoided. Adequate sleep is also important.
Dietary supplements that can enhance fertility include:
- Multivitamins can help treat infertility in women.
- Vitamin E has antioxidant activity that prevents reproductive damage in men and women. It can increase sperm count and motility in men and balance hormones in women.
- Vitamin C has antioxidant activity that prevents reproductive damage in men and women. Also, a study found that vitamin C supplementation led to improved sperm count and decreased sperm clumping in infertile men.
- Folic acid (with a multivitamin) improved fertility in a study of infertile women.
- Zinc deficiency is often associated with low sperm count. Studies have found that zinc supplementation can improve male fertility.
- Arginine supplementation led to major increases in sperm count and motility in a study of infertile men.
- Selenium has antioxidant activity. Selenium supplementation led to increased sperm count and motility and decreased number of abnormal sperm in a study of infertile men.
- Beta-carotene supplementation can increase sperm count and motility.
- B vitamins (B2, B6, and B12) are important for optimal fertility.
Herbal and Chinese medicine
The following may be taken by women to treat infertility:
- Dong quai (Angelica sinensis) has been used to regulate menstrual cycles and for infertility.
- Licorice helps to balance levels of estrogen and testosterone and is used for infertility.
- Red clover (Trifolium pratense) has a beneficial effect on the uterus, can calm the nervous system, and can balance hormone levels.
- Nettle (Urtica dioica) supports the uterus and hormonal system.
- Raspberry leaf strengthens the mucous lining of the uterus.
- Chasteberry (Vitex agnus-castus) balances hormone production.
- Ladies mantle (Alchemilla vulgaris) balances hormone production.
- Shatavari (Asparagus racemosus) is an Ayurvedic remedy for infertility and works by balancing hormones.
- Rehmannia is an Ayurvedic remedy for infertility.
- Myrrh (Commiphora myrrha) is an Ayurvedic remedy for infertility.
- False unicorn (Chamaelirium luteum) balances hormone levels.
- Pomegranate essence balances the reproductive system.
The following may be taken by men to treat infertility:
- Ginseng may increase the formation of sperm, testosterone levels, and sexual activity.
- Pygeum may help infertile men who have a reduced secretion of semen.
- Pine bark extract improves sperm shape.
- Chasteberry (Vitex agnus-castus) balances hormone production.
- Shatavari (Asparagus racemosus) is an Ayurvedic remedy for infertility and works by balancing hormones. May increase sperm production.
- Saw palmetto (Serenoa serrulata) increases the production of testosterone and strengthens the reproductive system.
- Ashwaganda (Withania omnifera) is an Ayurvedic remedy that improves the quality of semen and sperm count.
- Chinese herbals must be specifically designed and used to treat infertility in males.
A variety of other alternative treatments may be used for infertility:
- stress reduction
- cognitive behavior therapy
- essential oils
The first step in the treatment of infertility is to perform thorough physical exams and testing of both partners in the hope of finding the source of infertility. For the woman this involves blood testing and ultrasound examinations at specific days during the menstrual cycle. This may include an endometrial biopsy in which a sample of the lining of the uterus is taken and examined. Hysteroscopy, in which a special camera examines the inside of the uterus, may be performed.
Pelvic adhesions can be treated during laparoscopy. The adhesions are cut using special instruments. Endometriosis can be treated with certain medications, but may also require surgery to repair any obstruction caused by adhesions.
Treatment of cervical factors includes antibiotics in the case of an infection, steroids to decrease production of anti-sperm antibodies, and artificial insemination techniques to completely bypass the cervical mucus.
Treatment of ovulatory problems depends on the cause. If a thyroid or pituitary problem is responsible, simply treating that problem can restore fertility. Medications that stimulate ovulation are clomiphene citrate (Clomid) that is taken by mouth and follicle stimulating hormone (Pergonal, Fertinex, and Follistim) that is given by injection. These drugs increase the risk of multiple births (twins, triplets, etc.) and may cause side effects.
Treatment of male infertility includes addressing known reversible factors first; for example, discontinuing any medication known to have an effect on spermatogenesis or ejaculation, as well as decreasing alcohol intake, and treating thyroid or other endocrine disease. Varicoceles can be treated surgically. Testosterone in low doses can improve sperm motility.
Other treatments of male infertility include collecting semen samples from multiple ejaculations, pooling them, and depositing them into the female's uterus during ovulation. When the male partner's sperm is proven to be absolutely unable to produce pregnancy, donor sperm may be used. Depositing the male partner's sperm or donor sperm by mechanical means into the female is called artificial insemination.
Assisted reproductive techniques include in vitro fertilization (IVF), gamete intrafallopian transfer (GIFT), and zygote intrafallopian tube transfer (ZIFT). These are usually used after other techniques to treat infertility (surgery, medications, and/or insemination) have failed.
IVF involves the use of drugs to induce the simultaneous production of many eggs from the ovaries, which are retrieved surgically or via ultrasound-guided needle aspiration through the vaginal wall. The ova and sperm are combined in a laboratory, where several of the ova may be fertilized. Cell division is allowed to take place up to the pre-embryo stage. While this takes place, the female may be given progesterone to ensure that her uterus is ready for implantation. Two or more pre-embryos are transferred to the female's uterus.
Success rates of IVF are still rather low. The national average success rate of IVF is approximately 27% but some centers have higher pregnancy rates. Because most IVF procedures put more than one embryo into the uterus, the chance for a multiple birth (twins or more) is greatly increased.
GIFT involves retrieval of both multiple ova and semen, and the mechanical placement of both within the female's fallopian tubes, where fertilization may occur.
In general, it is believed that about half of the couples who undergo a complete evaluation of infertility followed by treatment will ultimately have a successful pregnancy. About 5% of those couples who choose to not undergo evaluation or treatment will go on to conceive after a year or more.
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American Society for Reproductive Medicine. 1209 Montgomery Highway, Birmingham, AL 35216-2809. (205) 978-5000. <http://www.asrm.com>.
International Center for Infertility Information Dissemination. <http://www.inciid.org>.
RESOLVE. 1310 Broadway, Somerville, MA 02144-1779. (617) 623-1156. <www.resolve.org>.