Chlamydia and Infertility

Dr Kathryn Basford

Medically reviewed by

Dr Kathryn Basford

Last reviewed: 01 May 2019

The main cause of infertility worldwide

Woman sat in a balcony deck chair checking on her laptop if chlamydia is linked to infertility

Key takeaways

  • Chlamydia can result in infertility because it can cause damage to both male and female reproductive systems

  • If untreated, chlamydia infections can spread to the womb and fallopian tubes and can lead to pelvic inflammatory disease

  • Chlamydia can cause more 'ectopic pregnancies' where a fertilised egg starts growing somewhere other than the womb, where it's supposed to

  • Once you've had one ectopic pregnancy, your chances of having another one increase

Chlamydia is one of the main causes of infertility in the UK and around the world. The disease frequently has no symptoms for the majority of patients (is asymptomatic), so people often don't realise they've got it. Because of this, it's common for chlamydia not to be detected, and for it to spread to the body, causing damage to the reproductive system in both men and women.

How does chlamydia cause infertility?

Infertility can be defined as the inability to get pregnant despite frequent unprotected sex over the course of one year. In western countries like the UK, about 15% of couples are infertile. Men are responsible for the couple’s infertility in half of these cases.

Infertility can be caused by a combination of factors that stop a pregnancy from happening. This is usually the result of genetic factors (e.g. poor DNA quality in sperm) and environmental factors (e.g. stress, smoking).

The rise of obesity in rich countries has contributed to the rise in infertility rates, because women who are obese tend not to ovulate as efficiently as those who are not overweight.

Obesity, STIs and infertility

Obesity and sexually transmitted diseases (STIs) rank among the most important factors causing infertility.

Over the last decade alone, the infection rate of chlamydia has doubled in the UK. Since young teenagers often don't know about the risk of sexual infections, early infections with chlamydia are very common.

Due to a lack of education with regards to STIs and contraception, young women tend to get tested too late (if at all), which results in greater potential for damage to their fallopian tubes.

As for men, it has been widely shown that sperm quality and quantity has waned over the past three decades in the West. Many factors account for this change, such as smoking, alcohol consumption and stressful lifestyles.

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Chlamydia and female fertility

If left untreated, chlamydia can spread and infect other parts of the female reproductive system, in particular the uterus and fallopian tubes, which can result in pelvic inflammatory disease (PID). With one in five women with chlamydia developing PID, chlamydia is the most common cause of infertility in women.

PID sometimes develops without causing symptoms and just like chlamydia, it is often diagnosed too late. Over time, the disease causes blocking or scarring to the fallopian tubes, which leads to infertility as well as miscarriage, premature birth and stillbirth.

In other cases, PID can lead to an ectopic pregnancy, which represents a serious health risk for the mother.

Ectopic pregnancies due to chlamydia

When a woman gets pregnant, the egg is fertilised in the fallopian tubes before it moves to the womb (where it implants).

An ectopic pregnancy happens when the egg implants outside the womb, for example in one of the fallopian tubes (usually because the tubes are blocked). This happens when PID, which is often caused by chlamydia, has caused scarring to the fallopian tubes and blocked them.

Recent studies have shown that chlamydia damages the fallopian tubes, inflicting a series of small scars. This process does not necessarily cause any symptoms and it often goes unnoticed.

How common is ectopic pregnancy?

A little over 1% of all pregnancies in the UK are ectopic. The great majority of ectopic pregnancies result in miscarriage.

However, if the egg does implant in a fallopian tube, the woman needs to be treated or undergo surgery to remove the egg. Ectopic pregnancies are very dangerous and they can lead to internal bleeding.

Symptoms of ectopic pregnancy

The symptoms of ectopic pregnancy are often difficult to spot early on, and sometimes it might not be obvious until they become more serious.

You might have an ectopic pregnancy if you’ve missed a period, or if you have a positive pregnancy test and notice:

  • vaginal bleeding (often a brownish discharge that might come and go)
  • pelvic pain (usually on one side)
  • shoulder tip pain
  • pain or discomfort when using the toilet

If you have a positive pregnancy test and notice any of these symptoms, you should see a doctor as soon as possible.

If an ectopic pregnancy gets too big it can cause a rupture or tear in the fallopian tube. This is an emergency and surgery is usually needed to repair the area. The signs of a rupture are:

  • sudden and severe stomach pain
  • lightheadedness or dizziness
  • vomiting or feeling sick
  • fainting

You should go to A and E urgently if you have these symptoms, or phone 999.

Long-term consequences

Women who have already had an ectopic pregnancy are more likely to develop another one. Statistics show that 1 in 5 are likely to develop a second ectopic pregnancy, and about 1 in 3 will not manage to become pregnant again. About half of all women diagnosed with an ectopic pregnancy have babies later on.

Medically reviewed by:
Dr Kathryn Basford

Dr Kathryn Basford is a qualified GP who works as a GP in London, as well as with ZAVA. She graduated from the University of Manchester and completed her GP training through Whipps Cross Hospital in London.

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Last reviewed: 01 May 2019

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