Should you need urgent health advice please contact your GP or call NHS 111. In an emergency please visit A&E or call 999

We offer tailored content specific to your area. Check below to find your local area.

Choose your location for articles and services where your live:

Sexually transmitted infections (STIs) in pregnancy

It’s important to be aware of sexually transmitted infections (STIs).

If you’re pregnant, they can be more dangerous and may harm you or your baby. You will be offered a blood test for hepatitis B, HIV and syphilis as part of your antenatal care, usually by a midwife before 10 weeks gestation.

There are certain scenarios in which you are more likely to be at risk of testing positive for an infection that isn’t routinely tested for during pregnancy. If you think you or your baby might be at risk from any of these infections, speak to your midwife, maternity team or GP.

If you have any concerns regarding sexually transmitted infections, you can self-refer to a local sexual health clinic or GP. Many STIs can affect the health of your baby during pregnancy and after birth.


Hepatitis affects the liver, some people with hepatitis do not show symptoms but may be a carrier of the infection.

The virus is spread by having sex with an infected person without using a condom, and by direct contact with infected blood. If you have hepatitis B or are infected during pregnancy, you can pass the infection on to your baby at birth.

You’ll be offered a blood test for hepatitis B as part of your antenatal care. Babies who are at risk, such as those whose mother has hepatitis B, should be given the hepatitis B vaccine at birth to prevent infection and serious liver disease later on in life.

Hepatitis C is another form of hepatitis that is dangerous during pregnancy, it can only be spread by direct contact with the blood of an infected person. If you have hepatitis C, you may pass the infection on to your baby, although the risk is much lower than with hepatitis B or HIV.

Many people with hepatitis C are not aware that they are infected, but someone might be at risk if they:

  • share needles when taking illegal drugs
  • received a blood transfusion in the UK prior to September 1991, or blood products prior to 1986

Your baby can be tested for hepatitis C and, if they’re infected, they can be referred for specialist assessment.


Genital herpes is spread through unprotected genital contact with an infected person, including through unprotected oral sex with someone who has cold sores.

The infection causes painful ulcers or blisters around the genitals, and less severe outbreaks can occur for years afterwards.

You’ll require treatment if your first infection occurs during pregnancy. If an infection occurs towards the end of your pregnancy, or during labour, a caesarean section might be recommended so that the infection is not passed to your baby.

Tell your midwife or doctor if either you or your partner have recurring herpes or develop sores.

Human Immunodeficiency Virus (HIV)

HIV damages the cells in your immune system and reduces your ability to fight infections and disease. The virus can be spread through unprotected sex with an infected person, it can also be contracted by sharing needles with someone infected by HIV. You should seek medical advice as soon as possible if you think you might have come into contact with HIV.

A test is offered as a routine part of your antenatal care in the form of a blood test. Current evidence suggests that if you’re HIV positive, in good health and without symptoms of the infection you’re unlikely to be adversely affected by pregnancy.

However, HIV can be passed to your baby during pregnancy, birth or breastfeeding. You’ll be advised not to breastfeed your baby if you test positive.

If you’re diagnosed with HIV, you and your doctor will need to discuss the management of your pregnancy and birth to reduce the risk of infection for your baby.

Treatment in pregnancy greatly reduces the risk of passing on HIV to the baby – from 1 in 4 to fewer than 1 in 100. Your baby will be tested for HIV at birth, treated with regular medication from birth and retested at regular intervals for 18 months.


Syphilis can be spread through unprotected sexual contact with an infected person, including sharing sex toys. It is also possible to be spread through the sharing of needles.

Syphilis can cause problems for your unborn baby if left untreated, including miscarriage, stillbirth or a serious infection in the baby known as congenital syphilis.

It can be hard to know if you have syphilis and some people infected have no symptoms at all, this is why a test is offered as part of your antenatal care.

It is treated with a short course of antibiotics. Without treatment it is unlikely to go away and can spread to the brain, causing significant health complications. People who have tested positive for syphilis in the past and received treatment can catch it again.

Useful links

NHS – Infections that may affect your baby

Page last reviewed: 22-09-2021

Next review due: 22-09-2024