Infertility is the inability of a person, animal or plant] to reproduce by natural means
In humans, infertility may describe a woman who is unable to conceive as well as being unable to carry a pregnancy to full term. There are many biological and other causes of infertility, including some that medical intervention can treat.
[1] Infertility rates have increased by 4% since the 1980s, mostly from problems with fecundity due to an increase in age.
[2] About 40% of the issues involved with infertility are due to the man, another 40% due to the woman, and 20% result from complications with both partners.
The World Health Organization defines infertility as follows:
“ Infertility is “a disease of the reproductive system defined by the failure to achieve a clinical pregnancy after 12 months or more of regular unprotected sexual intercourse (and there is no other reason, such as breastfeeding or postpartum amenorrhoea). Primary infertility is infertility in a couple who have never had a child. Secondary infertility is failure to conceive following a previous pregnancy. Infertility may be caused by infection in the man or woman, but often there is no obvious underlying cause.
Primary vs. secondary infertility
Primary infertility is the absence of a live birth for women who desire a child and have been in a union for at least five years, during which they have not used any contraceptives.
The World Health Organization also adds that 'women whose pregnancy spontaneously miscarries, or whose pregnancy results in a still born child, without ever having had a live birth would present with primarily infertility'
While Secondary infertility is defined as the absence of a live birth for women who desire a child and have been waiting for at least five years since their last live birth, during which they did not use any contraceptives.
Effect of infertility:
Infertility may have profound psychological effects.
Like - Partners becoming more anxious to conceive, leading to increase in sexual dysfunction.
- Marital discord which often develops in infertile couples, especially when they are under pressure to make medical decisions.
- Women trying to conceive often have clinical depression rates similar to women who have heart disease or cancer.
- Even couples undertaking IVF face considerable stress.
- The emotional losses created by infertility include the denial of motherhood as a rite of passage;
- The loss of one’s anticipated and imagined life;
- Feeling a loss of control over one’s life;
- Doubting one’s womanhood;
- Changed and sometimes lost friendships;
- And, for many, the loss of one’s religious environment as a result of searching for solution, or support system.
Meanwhile, the emotional stress and marital difficulties are greater in couples where the infertility lies with the man.
Causes of Infertility
Sexually transmitted disease
Infections with the following sexually transmitted pathogens have a negative effect on fertility:
1 Chlamydia ptrachomatis,
Neisseria gonorrhoeae, and Syphilis.
A consistent association of Mycoplasma genitalium
Infection and female reproductive tract syndromes.
M. genitalium infection is associated with increased risk of infertility.[21][22]
Genetic: Genetics of infertility
A Robertsonian translocation in either partner may cause recurrent spontaneous abortions or complete infertility.
Other causes,
Factors that can cause male as well as female infertility are:
DNA damage
DNA damage reduces fertility in female ovocytes, as caused by smoking, other xenobiotic DNA damaging agents (such as radiation or chemotherapy) or accumulation of the oxidative DNA damage 8-hydroxy-deoxyguanosine
DNA damage reduces fertility in male sperm, as caused by oxidative DNA damage, smoking, other xenobiotic DNA damaging agents (such as drugs or chemotherapy) or other DNA damaging agents including reactive oxygen species, fever or high testicular temperature.
General factors:
Diabetes mellitus, thyroid disorders, adrenal disease
Hypothalamic-pituitary factors
Hyperprolactinemia-- if prolactin levels are high and the woman is not pregnant or breastfeeding, it may affect ovulation and fertility.
Hypopituitarism
The presence of anti-thyroid antibodies is associated with an increased risk of unexplained subfertility with an odds ratio of 1.5 and 95% confidence interval of 1.1–2.0.
Environmental factors
Toxins such as glues, volatile organic solvents or silicones, physical agents, chemical dusts, and pesticides.
Tobacco smokers are 60% more likely to be infertile than non-smokers. - smoking significantly increases the risk of infertility in both men and women. Smoking may also undermine the effects of fertility treatment. Even when a woman gets pregnant, if she smokes she has a greater risk of miscarriage.
Alcohol consumption - a woman's pregnancy can be seriously affected by any amount of alcohol consumption. Alcohol abuse may lower male fertility. Moderate alcohol consumption has not been shown to lower fertility in most men, but is thought to lower fertility in men who already have a low sperm count.
German scientists have reported that a virus called Adeno-associated virus might have a role in male infertility, though it is otherwise not harmful.
Other diseases such as chlamydia, and gonorrhea can also cause infertility, due to internal scarring (fallopian tube obstruction
Further information: Female infertility
The following causes of infertility may only be found in females. For a woman to conceive, certain things have to happen:
1: intercourse must take place around the time when an egg is released from her ovary;
2: the system that produces eggs has to be working at optimum levels; and her hormones must be balanced.
For women, problems with fertilisation arise mainly from either structural problems in the Fallopian tube or uterus or problems releasing eggs. Infertility may be caused by blockage of the Fallopian tube due to malformations, infections such as chlamydia and/or scar tissue.
For example, endometriosis can cause infertility with the growth of endometrial tissue in the Fallopian tubes and/or around the ovaries.
Endometriosis is usually more common in women in their mid-twenties and older, especially when postponed childbirth has taken place.
Another major cause of infertility in women may be the inability to ovulate.
Malformation of the eggs themselves may complicate conception. For example, polycystic ovarian syndrome is when the eggs only partially developed within the ovary and there is an excess of male hormones. Some women are infertile because their ovaries do not mature and release eggs. In this case synthetic FSH by injection or Clomid (Clomiphene citrate) via a pill can be given to stimulate follicles to mature in the ovaries.
Other factors that can affect a woman's chances of conceiving include being overweight or underweight, Being obese or overweight - in industrialized countries overweight/obesity and a sedentary lifestyle are often found to be the principal causes of female infertility. An overweight man also has a higher risk of having abnormal sperm or age as female fertility declines after the age of 30.
Submucosal fibroids - benign or non-cancerous tumors found in the muscular wall of the uterus, occurring in 30% to 40% of women of childbearing age. They may interfere with implantation. They can also block the fallopian tube, preventing sperm from fertilizing the egg. Large submucosal uterine fibroids may make the uterus' cavity bigger, increasing the distance the sperm has to travel.
Endometriosis - cells that are normally found within the lining of the uterus start growing elsewhere in the body.
Previous sterilization treatment - if a woman chose to have her fallopian tubes blocked. It is possible to reverse this process, but the chances of becoming fertile again are not high.
Medications
Some drugs can affect the fertility of a woman. These include:
NSAIDs (non-steroidal anti-inflammatory drugs) - women who take aspirin or ibuprofen long-term may find it harder to conceive.
Chemotherapy - some medications used in chemotherapy can result in ovarian failure. In some cases, this side effect of chemotherapy may be permanent.
Radiotherapy
If radiation therapy was aimed near the womans reproductive organs there is a higher risk of fertility problems.
Illegal drugs
Some women who take marijuana or cocaine may have fertility problems.
Sometimes it can be a combination of factors, and sometimes a clear cause is never established.
Males
Further information: Male infertility
The main cause of male infertility is low semen quality. In men who have the necessary reproductive organs to procreate, infertility can be caused by low sperm count due to endocrine problems, drugs, radiation, or infection. There may be testicular malformations, hormone imbalance, or blockage of the man's duct system. Although many of these can be treated through surgery or hormonal substitutions, some may be indefinite. Infertility associated with viable, but immotile sperm may be caused by primary ciliary dyskinesia.
Abnormal semen is responsible for about 75% of all cases of male infertility. Unfortunately, in many cases doctors never find out why. The following semen problems are possible:
Low sperm count (low concentration) - the man ejaculates a lower number of sperm, compared to other men. Sperm concentration should be 20 million sperm per milliliter of semen. If the count is under 10 million there is a low sperm concentration (subfertility).
No sperm - when the man ejaculates and there is no sperm in the semen.
Low sperm mobility (motility) - the sperm cannot "swim" as well as it should.
Abnormal sperm - perhaps the sperm has an unusual shape, making it more difficult to move and fertilize an egg.
Sperm must be the right shape and able to travel rapidly and accurately towards the egg. If the sperm's morphology (structure) and motility (movement) are wrong it is less likely to be able to reach the egg and fertilize it.
Causes of abnormal semen
Testicular infection
Testicular cancer
Testicular surgery
Overheating the testicles - frequent saunas, hot tubs, very hot baths, or working in extremely hot environments can raise the temperature of the testicles. Tight clothing may have the same effect on some people.
Ejaculation disorders - for some men it may be difficult to ejaculate properly. Men with retrograde ejaculation ejaculate semen into the bladder. If the ejaculatory ducts are blocked or obstructed the man may have a problem ejaculating appropriately.
Varicocele - this is a varicose vein in the scrotum that may cause the sperm to overheat.
Undescended testicle - one (or both) testicle fails to descend from the abdomen into the scrotum during fetal development. Sperm production is affected because the testicle is not in the scrotum and is at a higher temperature. Healthy sperm need to exist in a slightly lower-than-body temperature. That is why they are in the scrotum, and not inside the body.
Hypogonadism - testosterone deficiency can result in a disorder of the testicles.
Genetic abnormality - a man should have an X and Y chromosome. If he has two X chromosomes and one Y chromosome (Klinefelter's syndrome) there will be an abnormal development of the testicles, low testosterone, and a low sperm count (sometimes no sperm at all).
Mumps - this viral infection usually affects young children. However, if it occurs after puberty inflammation of the testicles may affect sperm production.
Hypospadias - the urethral opening is at the underside of the penis, instead of its tip. This abnormality is usually surgically corrected when the male is a baby. If it is not the sperm may find it harder to get to the female's cervix. Hypospadias occur in about 1 in every 500 newborn boys.
Cystic fibrosis - Cystic fibrosis is a chronic disease that affects organs such as the liver, lungs, pancreas, and intestines. It disrupts the body's salt balance, leaving too little salt and water on the outside of cells and causing the thin layer of mucus that usually keeps the lungs free of germs to become thick and sticky. This mucus is difficult to cough out, and it clogs the lungs and airways, leading to infections and damaged lungs. Males withcystic fibrosis commonly have a missing or obstructed vas deferens (tube connecting the testes to the urethra; it carries sperm from the epididymis to the ejaculatory duct and the urethra).
Radiotherapy - radiation therapy can impair sperm production. The severity usually depends on how near to the testicles the radiation was aimed.
Some diseases - the following diseases and conditions are sometimes linked to lower fertility in males: Anemia, Cushing's syndrome, Diabetes, Thyroid disease.
Combined infertility
In some cases, both the man and woman may be infertile or sub-fertile, and the couple's infertility arises from the combination of these conditions. In other cases, the cause is suspected to be immunological or genetic; it may be that each partner is independently fertile but the couple cannot conceive together without assistance.
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