Thrush in Pregnancy: Symptoms, Causes, and Safe UK Treatments

Vaginal thrush, medically known as vulvovaginal candidiasis, is a yeast infection caused by an overgrowth of Candida albicans. While thrush is a frequent occurrence for many women, it is particularly common during pregnancy. Statistics suggest that pregnant women are up to three times more likely to develop thrush than those who are not pregnant.

This increased susceptibility is largely due to the high levels of oestrogen in the body. Oestrogen causes the vagina to produce more glycogen, which provides a rich food source for the yeast to multiply. Furthermore, changes in vaginal pH levels during the three trimesters make it easier for the yeast to thrive and adhere to the vaginal walls. While uncomfortable, it is important to remember that thrush is not a sexually transmitted infection (STI), though it can occasionally be triggered by sex.

The symptoms of thrush during pregnancy are broadly similar to those experienced at other times, though they can sometimes be more persistent or severe due to the constant hormonal environment. In the UK, the NICE (National Institute for Health and Care Excellence) guidelines highlight the following signs:

• Vaginal discharge: This is typically thick, white, and often described as looking like cottage cheese. It should not have a strong or foul smell.
• Itching and soreness: Intense itching around the entrance of the vagina and the labia.
• Stinging: A stinging sensation when passing urine or during sexual intercourse.
• Redness and Swelling: The vulval area may look red, inflamed, or slightly swollen.

If you notice a thin, grey discharge or a strong fishy odour, you may have bacterial vaginosis (BV) rather than thrush. It is vital to get a correct diagnosis as the treatments for these two conditions are different.

If you are pregnant, you must be cautious about the medications you use. In the UK, the standard first-line treatment for thrush in pregnancy involves antifungal creams or vaginal pessaries containing clotrimazole. Unlike the general population who might use a single-dose treatment, NICE guidance often recommends a longer course—typically 7 days—to ensure the infection is cleared effectively.

Important Note on Oral Tablets: Antifungal tablets, such as fluconazole (brand names like Canesten Duo oral capsule), are generally avoided during pregnancy. Research suggests a potential, though small, risk to the developing baby when taken orally. Always consult a GP or pharmacist before starting any treatment. When using a pessary, it is recommended to insert it by hand rather than using the plastic applicator provided, to avoid any risk of irritation to the cervix.

Self-Care Tips

• Wash the vaginal area with plain water or a soap substitute; avoid scented wipes or bubble baths.
• Wear loose-fitting cotton underwear to allow the area to 'breathe'.
• Avoid tight tights or synthetic fabrics that trap moisture.
• Consider using an emollient cream to soothe the external skin.

Managing a pregnancy is a busy time, and it may not always be convenient to visit a local surgery for minor infections. You should consider booking a consultation with a UK online doctor if:

• This is the first time you have experienced thrush symptoms during your pregnancy.
• Over-the-counter treatments have not worked after 7 to 14 days.
• The itching is so severe that it is causing broken skin or bleeding.
• You are unsure if your symptoms are thrush or another condition like an STI or BV.
• You are suffering from recurrent thrush (four or more episodes in a year).

An online GP can review your symptoms, provide advice aligned with NHS protocols, and, if necessary, issue a prescription for pregnancy-safe treatments to be collected at a local pharmacy. They can also provide a sick note if your symptoms are significantly affecting your ability to work.

A common worry for expectant mothers is whether the yeast infection will harm their baby. The good news is that vaginal thrush does not affect the baby’s development in the womb. The infection is localised to the vaginal environment and does not cross the placenta.

However, if you have an active thrush infection at the time of delivery, the baby can catch it as they pass through the birth canal. This usually manifests as oral thrush in the newborn—characterised by white patches in the baby's mouth—or a persistent nappy rash. Both are easily treated by a GP or health visitor and are not considered dangerous. Treating your thrush effectively before your due date reduces this risk.