Thrush and Other Infections in Pregnancy

Why thrush is more common now

The NHS explains it in one line: "During pregnancy, women can get thrush because of the changes going on in the body, especially during the third trimester." Cochrane's review of treatment in pregnancy puts it the same way — vaginal candidiasis is common generally, and "it is even more common in pregnancy".

The reassuring part comes with equal confidence. The NHS: "There's no evidence that thrush can harm an unborn baby." Cochrane: "There is no evidence that thrush in pregnancy is harmful to the baby." If the yeast is passed to your baby during birth, it is treatable and easily dealt with.

So thrush in pregnancy is a comfort problem, not a danger — but a comfort problem with a pregnancy-specific treatment rule that catches people out.

What it feels like

The NHS lists the symptoms as:

• "white discharge (like cottage cheese), which does not usually smell"
• "itching and irritation around the vagina and vulva"
• "soreness and stinging during sex or when you pee"

It also notes that redness can be harder to see on brown and black skin, which is worth flagging because "look for redness" is unhelpful advice for a lot of people. The HSE describes the same picture: itching and soreness of the vulva and vagina, thick white discharge, discomfort during sex and stinging when you pee.

The absence of smell is one of the more useful discriminators. Thrush usually does not smell.

What else it might be

Bacterial vaginosis

BV is the most commonly confused alternative, and the treatment is completely different — antibiotics rather than antifungals. The NHS describes the giveaway as "an unusual vaginal discharge that has a strong fishy smell, particularly after sex", with discharge that is "greyish-white, thin and watery", and notes that soreness and itching typically do not occur. Half of women with BV have no symptoms at all. On pregnancy the NHS is measured: there is "a small chance of complications, such as premature birth or miscarriage", but BV "causes no problems in the majority of pregnancies". NICE advises considering oral or vaginal antibiotics for BV in pregnancy.

A urinary tract infection

Stinging when you pee is a symptom shared by thrush and UTIs, and in pregnancy a UTI is the one that needs same-day attention. If the burning is inside rather than on the skin, if you are going constantly, or if you have a temperature or back pain, that is a urine sample, not a pessary.

Group B streptococcus

Not something you would notice, but worth knowing about. The RCOG explains that GBS "is a common bacterium (bug) which is carried in the vagina and rectum of 2–4 in 10 women" and usually causes no harm. If it is found in your urine during pregnancy you will be given antibiotics to treat that infection and offered antibiotics through a drip in labour. If it turns up on a vaginal or rectal swab, no treatment is given during pregnancy, but antibiotics are offered once labour starts.

Something sexually transmitted

NICE advises that if a sexually transmitted infection is suspected, clinicians should "consider arranging appropriate investigations" — and considering carrying out a vaginal swab "if there is doubt about the cause". Asking for a swab when a treatment has not worked is entirely reasonable.

When to call someone

• Speak to your GP or midwife before treating thrush in pregnancy. Both the NHS and the HSE say this explicitly, and the HSE adds: always tell a pharmacist you are pregnant before buying anything.
• Contact your midwife or GP if discharge smells unpleasant, is green, yellow or brown, or comes with itching, soreness or pain on passing urine — NICE treats this combination as an infection that "needs to be investigated and treated".
• Same day: burning on peeing with a temperature, back or side pain, or feeling generally unwell.
• Straight away: any vaginal bleeding, or fluid leaking or gushing before 37 weeks.

What actually helps

The right drug

NICE is unambiguous: "Offer vaginal imidazole (such as clotrimazole or econazole) to treat vaginal candidiasis in pregnant women." The Cochrane review backs this with numbers — across five trials, imidazole drugs were more effective than nystatin (odds ratio 0.21, 95% CI 0.16 to 0.29), and clotrimazole beat placebo (OR 0.14, 95% CI 0.06 to 0.31).

The right length of course

This is the finding most people have never heard. Cochrane found that four-day treatment was markedly less effective than seven-day treatment (OR 11.7, 95% CI 4.21 to 29.15, across two trials of 81 women), and concluded: "Treatments for seven days may be necessary in pregnancy rather than the shorter courses more commonly used in non-pregnant women." Their plain-language summary puts it starkly — seven-day courses cured more than 90% of women, while standard four-day courses cured about half. The HSE's advice matches: use an antifungal cream for a minimum of seven days.

The evidence base is old, and the review notes that later studies awaiting assessment could change the conclusions. But it is what current practice rests on, and it explains why a one-day treatment that works for a friend may not work for you now.

The wrong drug

The NHS is direct: "if you're pregnant, trying to get pregnant or breastfeeding, you should not take anti-thrush tablets". That rules out the single oral fluconazole capsule that is the default for many people outside pregnancy. The HSE says the same. This is the single most important thing on this page.

Reducing the chances of it coming back

The HSE suggests cotton underwear and loose clothing, avoiding perfumed products, using an emollient soap substitute, changing out of damp swimwear promptly, and ordinary genital hygiene. Notice what is not on that list: none of the guidance reviewed here recommends probiotics, live yoghurt or dietary changes. The trials that exist are trials of topical antifungals, and that is what the recommendations follow.

The short version

Thrush is common, harmless to your baby, and treated with a clotrimazole-type pessary or cream for seven days — not with tablets. Ask before you treat, and if it does not settle, ask for a swab rather than a second box of the same thing.