BV, Thrush and UTIs in Pregnancy: What Is Treated and Safe

If you are pregnant and think you have BV, thrush or a urinary infection, speak to your midwife or GP first: all three have a treatment in pregnancy, and the choice changes. The NHS says some thrush medicines should not be used while you're pregnant, NICE says a UTI in pregnancy gets an antibiotic immediately, and BV gets one when it causes symptoms. Live cultures showed no safety problems and no benefit in four trials.^{1, 2, 3, 4} Part of the Wellgard guide to what BV is and why it starts.

Why does pregnancy change the picture?

The NHS lists pregnancy among the conditions in which thrush develops and among the things that help bacteria reach the bladder.^{5, 6} Discharge also increases: NICE says it "is common during pregnancy", but itching, soreness, an unpleasant smell or pain on passing urine may mean an infection, with a swab "if there is doubt about the cause".³ So a midwife or GP decides; the three are different infections, and the evidence for any ingredient belongs to one only.

Is BV common in pregnancy, and does it matter?

Common and usually harmless. The NHS says there is "a small chance of complications, such as premature birth or miscarriage", and that BV "causes no problems in the majority of pregnancies".⁷ Across 32 studies and 30,518 pregnant women, BV without symptoms more than doubled the odds of preterm delivery (odds ratio 2.16) and raised the odds of late miscarriage (odds ratio 6.32).⁸ Antibiotics do not remove that risk in trials: in 21 trials of 7,847 women they eradicated BV (risk ratio 0.42) and reduced late miscarriage (two trials) but did not reduce preterm birth before 37 weeks (risk ratio 0.88; 13 trials, 6,491 women).⁹ No trial has tested screening itself, and antibiotics for women found by screening did not reduce preterm birth.¹⁰ Hence symptoms first: NICE says "Consider oral or vaginal antibiotics" for BV in pregnant women; its clinical summary says "Routine screening for BV should not be offered to pregnant women".^{3, 11} See what untreated BV leads to.

Is metronidazole safe in pregnancy?

UK guidance reaches for it: for symptomatic pregnant women "Oral metronidazole is the treatment of choice", with metronidazole gel or clindamycin cream as alternatives, and "Intravaginal clindamycin cream is not recommended in the first trimester".¹¹ On birth defects the pooled studies agree: odds ratios of 0.93 (1995, seven studies), 0.96 and 1.08 (two analyses in a 2020 US review) and 1.15 (0.98 to 1.34, not significant; 2021, 24 studies).^{10, 12, 13} The 2021 review also pooled five observational studies and found higher odds of miscarriage (odds ratio 1.72), but its authors asked for randomised trials "to assess the role of the underlying infection": the women given it had an infection that itself raises miscarriage risk, so the figure cannot separate medicine from indication.¹³ Your GP or midwife weighs this and sets the dose and course. Outside pregnancy: how BV is treated in the UK.

How is thrush treated in pregnancy?

With a cream or pessary first, after advice. The NHS says "If you get thrush when you're pregnant, it can easily be treated", and to talk to your doctor, pharmacist or midwife because "there are some thrush medicines you should not use while you're pregnant".¹ Its fluconazole page says the oral tablet "may sometimes be prescribed during pregnancy but only if other treatments have not worked", and a GP "will probably prescribe clotrimazole, or a similar antifungal medicine, first", as a cream or pessary; NICE says "Offer vaginal imidazole".^{3, 14} In a Danish cohort of 1.4 million pregnancies, oral fluconazole at 7 to 22 weeks was associated with more spontaneous abortions (hazard ratio 1.48, 1.23 to 1.77).¹⁵ Thrush is common in pregnancy, and pregnancy is itself a "see a GP" reason.⁵ Dangerous? The Cochrane review of ten trials opens with "There is no evidence that thrush in pregnancy is harmful to the baby"; course length is the prescriber's call.¹⁶ See vaginal thrush and what causes thrush.

Are UTIs in pregnancy always treated, and why?

Yes. NICE says "Offer an immediate antibiotic prescription" to pregnant women with a lower UTI, after a urine sample has gone for culture; bacteria found without symptoms get an antibiotic too, because in pregnancy they are "a risk factor for pyelonephritis and premature delivery".² Which antibiotic? The GP chooses from those NICE lists as suitable in pregnancy, guided by the culture result. In the Cochrane review, antibiotics for symptomless bacteria may reduce kidney infection (risk ratio 0.24, low-certainty evidence).¹⁷ On the NHS UTI page, pregnancy is itself a reason to "Ask for an urgent GP appointment or get help from NHS 111".⁶ UTIs are "usually caused by bacteria from poo entering the urinary tract", pregnancy heads the NHS risk list, and the NHS says ask your doctor before cranberry or D-mannose in pregnancy.⁶ Outside pregnancy: cystitis and the red flags, recurrent UTIs and can a UTI go away on its own.

Can live cultures be taken in pregnancy, and do they help?

Four trials found no safety problems and no benefit. In four UK maternity units, 304 women took two lactobacillus strains (2.5 billion CFU each) or placebo daily to delivery: BV at 18 to 20 weeks was 15% against 9%, not significant, and the capsules "did not modify the vaginal microbiota".⁴ In Canada, 86 women took the same pair for 12 weeks: 30% of both groups normalised, with "no adverse issues".¹⁸ In two Israeli trials of a six-species capsule (100 and 47 women), infections were 29% against 27% and 67% against 48%, neither significant.^{19, 20} A 2026 pooled analysis of 18 studies and 3,705 women found no significant effect on BV (odds ratio 0.91) or thrush (odds ratio 0.65).²¹ "Safe" is not a benefit: ask your midwife or GP before any supplement, and anyone with a weakened immune system, a central line or a serious illness asks a pharmacist or GP first. More: taking live cultures while pregnant or breastfeeding.

What should never be used in pregnancy?

Boric acid pessaries: UK and US guidelines "recommend IBA avoidance in pregnancy" and "safety data are sparse" (boric acid is never used in pregnancy).²² Oral antifungal tablets, unless a GP has prescribed one after creams have failed.¹⁴ Douches, deodorants and perfumed soaps or bath products.^{1, 5} A cream or pessary nobody has advised, including one bought online; antifungal creams also damage condoms and diaphragms.⁵ Home remedies inserted into the vagina: no trial, no NHS page. For a urinary infection, nothing you drink is a treatment.⁶

Can a miscarriage cause a UTI, and can a UTI affect the pregnancy?

No study has tested whether a miscarriage causes a UTI, and no NHS page lists either as a cause of the other; pain or bleeding in pregnancy means contacting your midwife or doctor immediately.¹ A UTI can affect the pregnancy if it climbs: the NHS warns that some UTI symptoms "could be symptoms of a kidney infection", which "can be serious if it's not treated as it could cause sepsis".⁶ That risk, with premature delivery, is NICE's reason for giving every UTI, and even silent bacteria, an antibiotic at once.²

When do I call the midwife, the maternity unit or 999?

Call your midwife if your discharge "smells unpleasant or strange", is green or yellow, or comes with itch, soreness or pain when you pee; contact your midwife or doctor immediately if "you have any vaginal bleeding while you're pregnant".¹ For urinary symptoms, pregnancy alone means an urgent GP appointment or NHS 111; so do a very high or low temperature, shivering, pain in the lower tummy or back under the ribs, blood in your pee, or symptoms that worsen or have not improved within 48 hours.⁶ Call 999 or go to A&E if you are confused, drowsy or have difficulty speaking.⁶ Also: folic acid in pregnancy and vitamin D in pregnancy.

Frequently asked questions

Can you use thrush cream when pregnant?

After advice, yes: talk to your doctor, pharmacist or midwife first; a GP "will probably prescribe clotrimazole, or a similar antifungal medicine, first", as a cream or pessary.^{1, 14}

Is BV dangerous in pregnancy?

Rarely. Pooled studies of 30,000 pregnancies found BV roughly doubled the odds of preterm birth, yet the NHS says it "causes no problems in the majority of pregnancies"; an antibiotic is given when it causes symptoms.^{7, 8}

Can I take live cultures while pregnant?

Four placebo-controlled trials, including a UK trial of 304 women, found live cultures taken in pregnancy neither reduced BV or thrush nor caused safety problems.^{4, 18, 19, 20} A finding, not a recommendation: ask your midwife or GP first.

Will a UTI harm my baby?

One dealt with promptly is unlikely to. The risk NICE names is kidney infection and premature delivery, which is why every UTI in pregnancy gets an antibiotic at once.²

Sources

1. NHS. Vaginal discharge in pregnancy. Reviewed 17 April 2024. nhs.uk.
2. NICE NG109. Urinary tract infection (lower), 1.1.5 to 1.2.2. 31 October 2018. nice.org.uk.
3. NICE NG201. Antenatal care, 1.4.10 to 1.4.14. 19 August 2021. nice.org.uk.
4. Husain S, et al. BJOG, 2020. PubMed 30932317.
5. NHS. Thrush in men and women. Reviewed 28 July 2023. nhs.uk.
6. NHS. Urinary tract infections (UTIs). Reviewed 11 July 2025. nhs.uk.
7. NHS. Bacterial vaginosis. Reviewed 19 June 2026. nhs.uk.
8. Leitich H, Kiss H. Best Practice & Research Clinical Obstetrics & Gynaecology, 2007. PubMed 17241817.
9. Brocklehurst P, et al. Cochrane Database of Systematic Reviews, 2013. PubMed 23440777.
10. Kahwati LC, et al. JAMA, 2020. PubMed 32259235.
11. NICE Clinical Knowledge Summaries. Bacterial vaginosis. Last revised July 2023. cks.nice.org.uk.
12. Burtin P, et al. American Journal of Obstetrics and Gynecology, 1995. PubMed 7856680.
13. Ajiji P, et al. European Journal of Obstetrics & Gynecology and Reproductive Biology: X, 2021. PubMed 34136799.
14. NHS. Pregnancy, breastfeeding and fertility while taking fluconazole. Reviewed 9 March 2023. nhs.uk.
15. Mølgaard-Nielsen D, et al. JAMA, 2016. PubMed 26746458.
16. Young GL, Jewell D. Cochrane Database of Systematic Reviews, 2001. PubMed 11687074.
17. Smaill FM, Vazquez JC. Cochrane Database of Systematic Reviews, 2019. PubMed 31765489.
18. Yang S, et al. Nutrients, 2020. PubMed 32019222.
19. Yefet E, et al. Nutrients, 2024. PubMed 39771026.
20. Nachum Z, et al. Nutrients, 2025. PubMed 39940318.
21. Liu Z, et al. Acta Obstetricia et Gynecologica Scandinavica, 2026. PubMed 42047468.
22. Mittelstaedt R, et al. Sexually Transmitted Diseases, 2021. PubMed 34561373.