Infertility refers to an inability to conceive after having regular unprotected sex. Infertility can also refer to the biological inability of an individual to contribute to conception, or to a female who cannot carry a pregnancy to full term. In many countries infertility refers to a couple that has failed to conceive after 12 months of regular sexual intercourse without the use of contraception.
Studies indicate that slightly over half of all cases of infertility are a result of female conditions, while the rest are caused by either sperm disorders or unidentified factors.
According to The Mayo Clinic, USA:
- About 20% of cases of infertility are due to a problem in the man.
- About 40% to 50% of cases of infertility are due to a problem in the woman.
- About 30% to 40% of cases of infertility are due to problems in both the man and the woman.
According to the Department of Health and Human Services, USA, approximately 10% to 15% of couples in the USA are infertile - meaning they have not conceived after at least one year of regular, unprotected sex.
Many cases of apparent infertility are treatable. Infertility may have a single cause in one of the partners, or it could be the result of a combination of factors.
Use this page to learn what causes infertility. Also get an overview of risk factors and how infertility is diagnosed. We outline the treatment options available, including IVF and surgery, and the complications caused by infertility.
Contents of this article:
You will also see introductions at the end of some sections to any recent developments that have been covered by MNT's news stories.
Chances of conceiving within one year
In Europe, North America and much of the world approximately 85% of couples will conceive within one year if they have regular unprotected sex. Averages in the UK are as follows (National Health Service):
- 20% will conceive within one month
- 70% will conceive within six months
- 85% will conceive within 12 months
- 90% will conceive within 18 months
- 95% will conceive within 24 months.
Therefore, doctors in the UK will not usually diagnose a couple as infertile until 24 months have passed without conception and regular unprotected sex. Most people will see their GP (general practitioner, primary care physician) if there is no pregnancy within 12 months.
According to the National Health Service, UK, a couple that has been trying to conceive for over three years has a maximum 25% chance of conceiving over the subsequent 12 months if they continue trying.
Risk factors of infertility
In medicine, a risk factor is something that raises the risk of developing a condition, disease or symptom. For example, obese people are more likely to develop diabetes type 2 compared to people of normal weight; therefore, obesity is a risk factor for diabetes type 2.
Age - a woman's fertility starts to drop after she is about 32 years old, and continues doing so. A 50-year-old man is usually less fertile than a man in his 20s (male fertility progressively drops after the age of 40).
Smoking significantly increases your risk of infertility
Smoking - 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.
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 has a higher risk of having abnormal sperm.
Eating disorders - women who become seriously underweight as a result of an eating disorder may have fertility problems.
Over-exercising - a woman who exercises for more than seven hours each week may have ovulation problems.
Not exercising - leading a sedentary lifestyle is sometimes linked to lower fertility in both men and women.
Sexually transmitted infections (STIs) - chlamydia can damage the fallopian tubes, as well as making the man's scrotum become inflamed. Some other STIs may also cause infertility.
Exposure to some chemicals - some pesticides, herbicides, metals (lead) and solvents have been linked to fertility problems in both men and women.
Mental stress - studies indicate that female ovulation and sperm production may be affected by mental stress. If at least one partner is stressed it is possible that the frequency of sexual intercourse is less, resulting in a lower chance of conception.
On the next page we look at the causes of infertility in women and men and how infertility is diagnosed. On the final page we discuss treatments for infertility.