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Bacterial vaginosis in pregnancy

Bacterial vaginosis (BV) is a common infection of the vagina.

It can cause a change in your vaginal discharge. It can also cause your discharge to have an unusual odour (smell).

For most pregnancies, bacterial vaginosis does not cause any problems. But in some cases, there’s a risk of complications, such as premature birth or miscarriage.

Bacterial vaginosis is easy to treat.

Talk to your GP, midwife or obstetrician if you think you have BV.

Symptoms of bacterial vaginosis

The symptoms of bacterial vaginosis are usually:

  • a change in the colour of your normal vaginal discharge
  • an unusual smell coming from your vagina or discharge

Your discharge may become more watery. It might also look grey in colour.

The unusual smell is sometimes compared to the smell of raw fish.

Cause of bacterial vaginosis

The cause of bacterial vaginosis is not fully understood. But it happens when the type of bacteria in your vagina changes.

In your vagina you have a mixture of bacteria. This includes 'friendly' or 'good' bacteria called lactobacilli.

If the friendly bacteria die off, other types of bacteria begin to grow. These are called anaerobic bacteria.

This change in bacteria upsets the acid balance of your vagina. This can cause more 'unfriendly' anaerobic bacteria to grow and cause BV.

Diagnosis of bacterial vaginosis

If you notice a change in the colour or smell of your vaginal discharge, talk to your GP, obstetrician or midwife.

They may ask you some questions about the discharge. They may also examine you by looking at your vagina. A vaginal swab is often the best way to confirm bacterial vaginosis.

A vaginal swab looks like a long cotton bud (or q-tip). It is inserted into your vagina and wiped against any discharge or the inside of your vagina.

Most GPs, GP practice nurses and midwives use a speculum to take the swab. This is a small plastic device that is inserted into your vagina and opened gently.

Once they take the swab, it will be sent to the nearest microbiology lab for analysis.

Vaginal swabs do not usually hurt, but they may be a little uncomfortable. They do not harm your baby.

Treatment of bacterial vaginosis

Your GP or obstetrician can prescribe medication to treat bacterial vaginosis.

The treatment is usually an antibiotic. It may come as tablets, a cream or a gel.

Always follow the instructions given to you by your GP, obstetrician or pharmacist.

Self-management of bacterial vaginosis

As well as the treatment above, there are things you can do to self-manage bacterial vaginosis.


When you are washing your genitals, you can just use plain water.

If you would like to use something else to wash your genitals, don't use soap or shower gel. Instead, use an emollient like aqueous cream.

Soap can irritate the skin and alter the pH balance in the vagina. It is never recommended for washing genital area.

If you are using an emollient, be careful as they can make your bath or shower very slippery.

It is better to take showers rather than baths if you have bacterial vaginosis. Bathing is more likely to alter the pH balance in your vagina because you are sitting in the water. You do not need to clean your vagina more than once per day.


  • Do not douche your vagina (a douche is flushing, squirting or spraying water or other cleaning products into your vagina)

  • Do not use tampons when you are pregnant - these can introduce harmful bacteria

  • Do not use shower gels, shampoo or antiseptics to wash your genitals

  • Do not use deodorants or vaginal washes


Smoking can affect your immune system. This can make you more prone to getting bacterial vaginosis.

Quitting smoking can reduce the chances of you getting BV.

Visit quit.ie for support and advice to help you quit smoking.

Antenatal perineal massage

It is not recommended to do perineal massage when you have bacterial vaginosis.

Perineal massage is a method of stretching your perineum. This is the skin between the vagina and the back passage. Perineal massage can help get your perineum ready for birth.

Page last reviewed: 17 May 2019
Next review due: 17 May 2022