STIs and Fertility: What You Need To Know-image

STIs and Fertility: What You Need To Know

There are dozens of STIs out there, all with different symptoms and characteristics. If you find out you have an STI, you’re gonorrhoea-lly want to sort it out quickly, so it is important to get an STI check-up if you develop any symptoms and get treated as soon as possible. If you do develop symptoms, you should avoid having sex without a condom until you have been treated to prevent the spread of the disease. 

General STI symptoms include:

  • Unusual discharge from your vagina or anus
  • A burning sensation, or pain, when you pee
  • Lumps and bumps around your vagina or anus, including a rash
  • Unusual bleeding
  • Genital or anal itching
  • Blisters or sores around your vagina or anus

Symptoms develop at different times for different infections and some can take a long time to show themselves. Most STIs can hide in the body and only display symptoms months or years after they were contracted. Because of this, it might be hard to trace where the infection came from, so you must tell everyone you have had sex with so they can be checked out too. 

To make things more complicated, lots of people don’t display any symptoms when they have an STI and so may not even know they have one. Because of this, it is also a good habit to have a test each time you have sex with someone new, even if you don’t have any symptoms. It’s better to be safe than sore-y! 

Key STI facts

  • STIs affect everyone
    • Although young people aged between 15-24 account for half of STIs diagnosed each year, nobody that is sexually active is exempt from catching an STI!
  • Barrier contraception is the only way to prevent STI transmission
    • Barrier contraception includes male and female condoms or a dam for female oral sex
    • It’s essential to use these when having sex with a new partner until you’re sure they’re STI free.
  • STIs can affect your fertility
    • This is generally due to long term infections causing scarring of your fallopian tubes, which can prevent your eggs from reaching your uterus
    • It may be possible to correct the scarring with surgery, but prevention is most effective
  • STIs can be passed to your baby during pregnancy
    • This can lead to pregnancy complications and your baby needing treatment upon delivery 

STIs and their symptoms


Chlamydia is the queen of STIs and is the number one most commonly transmitted STI in the UK. It is a bacterial infection which is spread through sex or contact with infected genital fluids, such as through genital contact or the sharing of sex toys. The infection can either be oral, genital or anal, meaning oral and anal sex can also pass on the disease! Infected genital fluids can also cause conjunctivitis if they come into contact with your eyes, either through genital contact or often from your fingers. If caught early, chlamydia can be treated easily with a short course of antibiotics but can become more complicated if left for a long time, causing conditions such as PID and infertility, and pregnancy complications. 

  • Symptoms:
    • A change in vaginal discharge
    • Pain when peeing
    • Bleeding between periods or after sex
    • Pelvic pain
    • 50% of men and 70% of women don’t show any symptoms


Gonorrhoea is another bacterial STI that is spread through sex or contact with a genital fluid. Like chlamydia, gonorrhoea can generally be easily treated with a course of antibiotics if caught early. Gonorrhoea is particularly good at changing itself to become resistant to antibiotics and recently there has been an increase in the spread of antibiotic-resistant “super-gonorrhoea” that is more difficult to treat1. A swab test will be able to identify which strain of gonorrhoea you have and allow the specialists to decide which is the best way to treat it. Gonorrhoea can also become more serious if not treated quickly, causing conditions such as PID and infertility, and pregnancy complications, so it is important to get yourself tested as soon as possible if you think you may have been exposed to the infection!

  • Symptoms:
    • A thick, green or yellow discharge 
    • Pain when peeing
    • 10% of men and 50% of women don’t show any symptoms


Not many people have heard of trichomoniasis and it is often quite hard to diagnose as the symptoms are very similar to those of other STIs. Trichomoniasis is caused by a tiny parasite which infects the genitals and is passed on through sex and contact with infected genital fluids. Further complications with trichomoniasis are rare, but if contracted during pregnancy it can cause premature birth and low birth weight. Having trichomoniasis can also make you more at risk of contracting additional STIs, including HIV. 

  • Symptoms:
    • A change in vaginal discharge, including the production of more discharge than normal, which can be thicker, thinner or frothy and yellow-green in colour and have an unpleasant fishy smell
    • Pain when peeing or having sex
    • Vaginal itchiness and discomfort 
    • 50% of men and women don’t show symptoms

Genital Warts

Genital warts are caused by a virus called the human papillomavirus (HPV), which might sound familiar, as this is the virus that is also linked to cervical cancer. But don’t worry, there are lots of different strains of HPV and the one which causes genital warts is not associated with cervical cancer. 

This STI is mainly spread through vaginal and anal sex but can also be passed through skin to skin contact of the genitals. The virus is more likely to be spread if genital warts are visible, but it’s still possible to pass it on even if there is no sign of the infection. 

Visible warts can be removed through a variety of treatments, including a cream, freezing, heat removal, surgery or laser treatment. These will remove visible warts, but it won’t clear the infection, so it can still be passed on to others. There is currently no cure for genital warts, but the body will usually clear the infection itself over time. The infection is generally more persistent in smokers and so it can take longer for your immune system to clear the virus, another good reason to quit! 

Although there are currently no treatments to cure genital warts, there is a vaccine available to prevent you from getting infected in the first place. This is called Gardasil and is given to all girls aged 12-13 years as part of the national vaccination programme. 

  • Symptoms:
    • Small lumps or bumps around the vagina or anus
    • Usually painless, but can be a bit itchy 
    • Most people who carry the virus which causes genital warts don’t have any visible warts themselves

Genital Herpes

Genital herpes is an STI caused by a virus, which is in the same family as the virus which causes cold sores. There is no cure for herpes, but the immune system will generally clear the infection on its own and there are therapies available to ease symptoms and prevent further outbreaks, including antiviral tablets, anaesthetic ointments and lubricants. Home remedies can also be helpful, such as bathing the area in saltwater and cooling the area with an ice pack or cool shower. 

Herpes is passed on through sexual contact, which can include sex, direct genital contact or receiving oral sex from someone with a cold sore. Infections are most likely to happen just before, during, or directly after an outbreak, but it is still possible to pass on the infection when you’re asymptomatic. If you’re pregnant, it is also possible to pass the virus to your baby if you have an outbreak around the time of delivery. 

  • Symptoms:
    • Small, sore blisters around the vagina
    • Pain when peeing
    • Tingling or itching around the vagina, generally present before an outbreak
    • Flu-like symptoms
    • Most people with the virus which causes genital herpes don’t show any symptoms for a long time

Pubic Lice 

Pubic lice are tiny parasitic insects that live in coarse pubic hair and are spread from person to person through close bodily contact. The lice move by crawling from hair to hair but can occasionally spread through contact with clothing or bedding used by someone with lice. Pubic lice have a crab-like appearance and so are more commonly known as “crabs”. They are related, but different, to head lice and like head lice, public lice survive on human blood, lay their eggs at the base of hairs. They are also not associated with poor hygiene. Treatment is easy and involves the application of a lotion or shampoo to the affected area. It is important to tell your specialist if you are pregnant or breastfeeding, as although you can still be treated, it may influence the type of treatment that you’re given. 

  • Symptoms:
    • Itching around your vagina, particularly at night
    • Inflammation 
    • Black powder in your underwear (louse droppings)
    • Blue spots, or small spots of blood, on your skin caused by bites


Syphilis is another STI which is caused by a bacterial infection, which is spread during sex or through contact with the ulcers of someone with syphilis. It is easily treated with a course of antibiotics if caught early but can have serious side effects if left untreated, causing damage to the heart, brain, bones and nervous system. Luckily, late syphilis is now rare in the UK and so these symptoms are extremely uncommon. 

Having syphilis makes you more at risk of contracting other STIs, such as HIV because the ulcers make it easier for other infections to get in. Although syphilis doesn’t affect fertility, it can have serious implications if you’re pregnant, including miscarriage, premature or stillbirth, or your baby being born with syphilis. Treatment can be given safely during your pregnancy, so it is important to tell your specialist if you think you might have syphilis to prevent this from happening. 

  • Symptoms:
    • Small painless sores on your vagina
    • A blotchy rash
    • Flu-like symptoms
    • Symptoms can come and go and are generally not apparent at first.


HIV (human immunodeficiency virus) is an STI caused by a virus which weakens your immune system so that it can’t fight off infections. If left untreated, an HIV infection can result in AIDS (acquired immunodeficiency syndrome). The symptoms of HIV are very generic and so it is often hard to diagnose. Because of this, the amount of virus in the body is often very high at the point of diagnosis, which will generally cause you to feel unwell.

HIV is mainly spread through vaginal or anal sex, or through sharing sex toys, but can also be spread from mother to baby during pregnancy, or when breastfeeding. You can avoid passing the infection onto your baby by taking medication and by avoiding breastfeeding. 

There is currently no cure for HIV, however, treatment is available to reduce the symptoms of the disease and prevent it being passed on, even if you have unprotected sex4. Despite this, the treatment must be taken for the rest of your life and the amount of virus in your body must be closely monitored to ensure that the drugs are still working. HIV can change itself very quickly to become resistant to medications, so treatment methods may have to be changed overtime to keep the amount of virus in your body low. 

If you think you have been, or will be, exposed to the virus, there are medications that you can take to protect yourself from getting it, which are called post-exposure prophylaxis (PEP) and pre-exposure prophylaxis (PrEP) respectively. These drugs prevent the virus from taking hold and spreading throughout your body, and so prevent you from becoming HIV positive and getting sick. 

An HIV positive person can have a baby with someone who is HIV negative without passing on the infection to their partner or their baby, but this is only the case if they are taking medication and their viral level is very low. Other people will need to have IVF treatment to prevent passing on the virus, as having sex without a condom may put their partner at risk. 

  • Symptoms:
    • Flu-like symptoms
    • A red rash on the body
    • HIV symptoms can be hard to detect as they are very generic and may pass even if the virus is still present 

STIs, fertility and pregnancy

STIs are not only sores, bumps and smelly discharge, they can also have a serious impact on your fertility. If left untreated, bacterial STIs such as chlamydia and gonorrhoea can cause pelvic inflammatory disease (PID), which is an infection of the upper genital tract (including the womb and fallopian tubes). This happens when the infection spreads up from the vagina to higher reproductive organs. 

Like other STIs, PID often comes with no symptoms and so can be hard to diagnose, but is often associated with pain, particularly during sex and periods. If PID becomes more serious, it can also cause a fever, nausea and vomiting. PID can be easily treated with antibiotics if caught early but can become more complicated if it is left untreated and causes infertility in one in ten women with the condition.

Chronic PID can cause scarring of the fallopian tubes, which causes them to narrow or become stuck together. This can make it difficult for eggs to travel from the ovaries to the womb, preventing you from getting pregnant. It can also increase your chances of fertilised eggs implanting in your fallopian tubes rather than your womb, which is called an ectopic pregnancy. Ectopic pregnancies are extremely serious and require immediate emergency medical attention. 

It’s also important to watch out for new or existing STIs if you are pregnant, as these can cause complications in your pregnancy. Common complications include premature birth, low birth weight, chorioamnionitis and miscarriage2,3. You can also pass the infection on to your baby during the delivery, which can cause different complications depending on the infection. For example, chlamydia and gonorrhoea can be transferred to your baby as they pass through the birth canal during the delivery and can cause eye and lung infections in your baby. These can be treated with antibiotics after birth. Other STIs that travel in the blood, which includes HIV, hepatitis and syphilis, can also be passed to your baby. 

Your midwife or doctor must be aware of any STIs that you have during your pregnancy to prevent any additional harm to your and your baby. Some treatments can be administered during pregnancy, which will help you clear the infection and avoid passing it on to your baby. Other STIs which do not have a cure may require further planning and intervention to avoid transmission, such as a caesarean section.



1. Bodie, M., Gale-Rowe, M., Alexandre, S., Auguste, U., Tomas, K. and Martin, I., 2019. Multidrug resistant gonorrhea: Addressing the rising rates of gonorrhea and drug-resistant gonorrhea: There is no time like the present. Canada Communicable Disease Report, 45(2-3), p.54.

2. Andrews WW, Goldenberg RL, Mercer B, Iams J, Meis P, Moawad A et al. The Preterm Prediction Study: association of second-trimester genitourinary Chlamydia infection with subsequent spontaneous preterm birth. Am J Obstet Gynecolo 2000;183;662–8.

3. Alger LS, Lovchik JC, Heel JR, Blackmon LR, Crenshaw Mc. The association of Chlamydia trachomatis, Neisseira gonorrhoeae, and group B streptococci with preterm rupture of the membranes and pregnancy outcome. Am J Obstet Gynecol 1988;159(2):397–404.

4. Rodger, A.J., Cambiano, V., Bruun, T., Vernazza, P., Collins, S., Van Lunzen, J., Corbelli, G.M., Estrada, V., Geretti, A.M., Beloukas, A. and Asboe, D., 2016. Sexual activity without condoms and risk of HIV transmission in serodifferent couples when the HIV-positive partner is using suppressive antiretroviral therapy. Jama, 316(2), pp.171-181.

Eloise Burt BSc (Hons) MSc

Eloise Burt BSc (Hons) MSc

Posts that author Eloise Burt has created for the Hertility Blog.

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