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What is infertility?

Infertility can be defined as the failure to achieve a pregnancy after 12 months or more of regular unprotected sexual intercourse. Infertility is much more common than most people imagine and can affect both men and women. Large population studies show that as many as one in six couples are affected at some time in their reproductive lives. Thankfully, most causes of infertility are amenable to fertility treatment.

Causes of infertility

Fertility problems can affect both men and women and there are many possible causes of infertility.

Natural conception is dependent upon several factors but essentially the female partner must produce an egg from one of her ovaries and the man a high number of good quality sperm to fertilise the egg. Regular intercourse every two or three days will increase the chances of fertilisation. Once fertilisation has occurred, the embryo must implant and develop which requires a normal uterus. If any of these processes are compromised at any stage, then the chance of a spontaneous conception is reduced and, in some cases, even impossible. 

For around one in five couples, there may be one or more explanation for their infertility. This could be an ovulation problem in the female partner and a sperm problem in the male partner.  In these cases, it is important that both causes are treated from the outset. In a third of cases, it isn't possible to identify the cause.

Infertility in women

Infertility causes in women can be due to a diverse range of problems. Common causes of infertility include:

  • maternal age
  • lack of regular ovulation, the monthly release of an egg
  • damaged or blocked fallopian tubes
  • endometriosis – where tissue that behaves like the lining of the womb (the endometrium) is found outside the womb

Find out more about female infertility here

Infertility in men

In men, the most common cause of infertility is poor quality and quantity of semen.

Find out more about male infertility here

Unexplained infertility

While one-third of all infertility cases can be explained by female causes and one-third by male, there remains a further third for which no clear explanation can be found despite investigations taking place and all the tests - for both male and female - show normal results. Couples who are said to have ‘unexplained infertility’ can still be treated successfully with the help of fertility treatment.

Primary and secondary infertility

There are two sources of infertility, one ‘primary’, the other ‘secondary’. The first describes a physiological condition in couples who have never been able to conceive, despite continued attempts; the second describes an acquired state of infertility in a couple who have had a successful natural pregnancy in the past.

Sub fertility

The chance of conceiving a pregnancy per cycle with regular sexual intercourse for most fertile couples is only around 25%. Most couples (around 90%) should therefore achieve a natural pregnancy within a year of regular intercourse (and 95% over two years). So, a long delay in conceiving might simply reflect low fertility rather than infertility.

Risk factors affecting fertility

There are also a number of key risk factors which do affect fertility in both men and women:

  • Age – female and male fertility to a lesser extent does decline with age. This is particularly so for women whose fertility starts to decline after the age of 35.
  • Weight – being overweight or obese reduces your fertility. We recommend a BMI of under 30 to give you an optimal chance of success.  We do however treat women with a BMI up to 35.
  • Smoking – can affect chances of conceiving in women and reduce semen quality in men. We recommend that you have given up smoking for at least three months before trying to conceive. 
  • Alcohol – the safest approach for women is not to drink if planning to get pregnant and for men too much alcohol can affect sperm quality. Once pregnant women should avoid drinking alcohol altogether.
  • Stress – in severe cases can affect ovulation and sperm production. In lesser a loss of sex drive. We do however understand that infertility and undergoing fertility treatment can be a stressful time.  Our monthly support group and counselling is available for all our patients. 

Book a fertility MOT test

To diagnose any fertility issues, we recommend a Fertility MOT. We have options for women, men, and couples. Find out more about each here:

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