Introduction

Vulvovaginal candidiasis (VVC), or thrush, is among the most common vaginal infections in pregnancy. Approximately 75% of women will be affected at least once in their lives, and rates notably climb during pregnancy.^3,4 This creates significant management challenges for obstetricians and midwives. This review evaluates current Australian evidence and practice guidelines for diagnosing and managing thrush in pregnancy.

Epidemiology and Microbiology

Candida species colonise the vagina in at least 20% of women, rising to about 30% during pregnancy.⁶ Most symptomatic cases result from the overgrowth of Candida albicans, although non-albicans species, such as C. glabrata or C. krusei, account for 10–20% of infections.^1,2 Thrush becomes more frequent in pregnancy due to physiological changes that promote candidal overgrowth. Infection may develop spontaneously or after disruption of the normal vaginal flora, commonly following antibiotics or increased oestrogen, as seen in pregnancy.

Pathophysiology in Pregnancy

Multiple factors increase the risk of thrush in pregnancy, most notably the hyperoestrogenic environment. High oestrogen levels raise vaginal glycogen, providing nutrients for fungi.^5,6 Oestrogen also induces Candida’s shift from harmless yeast to invasive hyphae, heightening its virulence.⁶

Pregnancy triggers changes in cell-mediated immunity, especially impacting T-helper cell responses.⁶ While these shifts are essential for feto-maternal tolerance, they inadvertently foster conditions that allow opportunistic infections, such as candidiasis.

Candida does not occur in a non-oestrogenised vaginal environment. This explains why VVC is rare in prepubertal girls or postmenopausal women not on oestrogen therapy.² Most cases of candidiasis are due to overgrowth of endogenous yeast rather than sexual transmission, although transmission can occur occasionally.^1,2

Risk Factors

In addition to pregnancy-specific factors, several other risk factors heighten VVC susceptibility in pregnant women.

Antibiotic Use: Recent or ongoing antibiotic therapy disrupts the protective lactobacillus-dominated vaginal microbiome, allowing Candida overgrowth.^1,2

Diabetes Mellitus: Both pre-existing and gestational diabetes significantly increase VVC risk. Hyperglycemia provides an improved substrate for fungal growth and may impair local immune responses.^3,4,6

Immunosuppression: HIV infection or other causes of immunocompromised states increase susceptibility to symptomatic infection.^1,2

High-Dose Hormonal Therapy: Use of higher-dose combined oral contraceptive pills or menopausal hormone therapy (important for pre-pregnancy counseling).³

Clinical Presentation

The most common symptom of thrush is itching or burning around the vulva. Other possible signs include:^3,4

• Thick, white, or creamy vaginal discharge (often resembling cottage cheese)^2,3
• Vaginal soreness²
• Superficial dyspareunia2
• Vulvar dysuria (external burning sensation during urination)^2,10
• Vulvar erythema and edema²
• Vulvar fissures and superficial erosions in severe cases²

The discharge often appears white and curd-like but may be yellow or green with marked inflammation.² Notably, VVC can be asymptomatic; colonisation without symptoms requires no treatment. Recognise that no symptom uniquely identifies VVC, which may be mistaken for conditions such as herpes, bacterial vaginosis, or dermatitis.^3,4,10

Diagnostic Considerations

Clinical Diagnosis

Most cases of uncomplicated VVC during pregnancy can be diagnosed clinically based on typical symptoms and examination findings. Vaginal pH measurement, when performed, usually shows a pH below 4.5, supporting the diagnosis² The presence of normal lactobacilli is generally maintained in VVC, unlike bacterial vaginosis.

Laboratory Investigation

Laboratory confirmation is advised in the following situations:^1,2

• Diagnostic uncertainty
• Recurrent infections (defined as 4 or more episodes in 12 months)¹Treatment failure
• Suspected non-albicans species

Microscopy can support diagnosis by showing budding yeasts, with or without pseudohyphae. Lactobacilli and a polymorphic inflammatory infiltrate are often present.² If microscopy is negative but symptoms suggest candidiasis, culture should follow. This step is needed for species identification when non-albicans species are suspected.^1,2

Microscopy and culture can produce false negatives after recent antifungal use and should be repeated if symptoms continue.^1,2 Importantly, yeasts are part of the normal vaginal flora, and culture positivity without symptoms does not require treatment.

Implications for Pregnancy Outcomes

The association between VVC and adverse pregnancy outcomes remains unclear. While infection can cause significant maternal discomfort and distress, no evidence links vaginal thrush in pregnancy to fetal harm.⁵

Some evidence indicates possible links with preterm birth, although large systematic reviews have shown inconsistent results.^9,12 The suggested mechanism involves chronic vaginal inflammation leading to prostaglandin release, which then causes cervical ripening and uterine contractions.⁶ However, causality has not been definitively proven.

Neonatal Considerations

Vertical transmission during vaginal delivery can lead to neonatal oral thrush or nappy candidiasis. Although these conditions are usually benign and treatable, premature infants may occasionally develop more severe invasive infections. Studies have looked at the presence of Candida on neonatal skin after delivery, but the clinical importance of such colonisation is still unclear.⁵

Congenital cutaneous candidiasis, although rare, is a more serious form of intrauterine infection, especially affecting preterm infants.⁶ However, this condition is uncommon and typically associated with specific risk factors, such as prolonged rupture of membranes and the use of intrauterine devices.

Management in Pregnancy

General Principles

Pregnant women with thrush should see their doctor before beginning any treatment. Management must weigh maternal symptom relief against fetal safety, with treatment choices significantly differing from those in non-pregnant populations.^3,4

Topical Antifungal Therapy

First-line treatment: Use topical imidazoles instead of nystatin whenever possible for symptomatic thrush during pregnancy^.5

Recommended regimens include:^1,2

• Clotrimazole: Vaginal cream or pessary for 3-6 nights, or 500mg pessary as a single dose
• Miconazole: Vaginal cream or pessary for six nights

Pregnant women should receive a seven-day treatment course, as this cures over 90% of infections, four-day courses cure just over half and courses longer than a week offer no added benefits.⁵

Vulval Symptoms: Applying topical 1% hydrocortisone cream (with or without a topical antifungal) may help relieve severe vulvitis symptoms. Treating only the vulva is insufficient because of the vaginal reservoir; therefore, both areas should be treated at the same time.^1,2

Important Considerations: All intravaginal treatments can weaken latex condoms. Patients should be advised accordingly, with treatment ideally applied after intercourse.^1,2

Oral Antifungal Therapy

Critical Contraindication: Oral fluconazole should not be used during pregnancy.^1,4 Although it is highly effective in non-pregnant women, fluconazole poses potential risks to the developing fetus, especially with first-trimester exposure.

Epidemiological studies have identified a connection between oral fluconazole use during pregnancy and increased risks of spontaneous abortion, congenital anomalies including heart defects, and other structural abnormalities^.6,10

Australian guidelines consistently recommend against the use of oral azole antifungals during pregnancy.^1,4

Asymptomatic Colonisation

There is no evidence to suggest that asymptomatic women need treatment.⁵ Routine screening and treatment of asymptomatic candidal colonisation are not recommended in Australian practice.^1,12 Treatment should be reserved for symptomatic infections that cause maternal discomfort.

Recurrent Candidiasis in Pregnancy

Recurrent candidiasis during pregnancy poses specific management challenges. Women should be evaluated for:^1,2

• Glycaemic control (including screening for gestational diabetes if not already done)
• Other immunosuppressive conditions
• Adherence to previous treatment regimens
• Potential presence of non-albicans species

For confirmed recurrent VVC in pregnancy, longer courses of topical antifungal therapy are recommended.⁵ Oral suppressive therapy, which is commonly used in non-pregnant women, is contraindicated during pregnancy.^1,4

Non-Albicans VVC

Non-albicans species are less responsive to azole antifungals and may show resistance. Most non-albicans infections are caused by Candida glabrata.² These species cause less inflammation than Candida albicans and may sometimes be asymptomatic.²

Standard topical azole antifungal treatments may be effective if administered for a longer duration during pregnancy, typically two weeks. Alternative options used outside of pregnancy (such as boric acid or amphotericin) require specialist consultation to assess safety during pregnancy.²

Self-Care Measures and Prevention

Australian guidelines emphasise the importance of self-management strategies:^1,3,4

Hygiene and Lifestyle Measures:

• Avoid local irritants, including soap, bath oil, body wash, bubble bath, and vaginal hygiene products.^1,3
• Wipe from front to back after toileting to prevent spread of Candida from the anus⁴
• Wear loose-fitting, breathable cotton underwear³
• Avoid tight synthetic clothing⁵
• Use simple emollients as soap substitutes³
• Maintain good glycaemic control if diabetic³

Products to Avoid:

• Perfumed products^1,3
• Vaginal douching^1,3
• Spermicides¹
• Vaginal lubricants (oil-based products can damage latex condoms)¹

Excessive washing and the use of bubble baths or perfumed soaps can harm the natural protective flora of the vagina and should be avoided.⁵ Applying topical 1% hydrocortisone cream may help relieve vulval symptoms.^1,2

Role of Probiotics

The evidence supporting the use of probiotics for preventing or treating VVC during pregnancy remains limited. Currently, there is no evidence that specific diets or probiotics affect recurrence rates according to Australian guidelines.¹ While some international studies show potential benefits, routine probiotic use is not recommended in Australian obstetric practice for VVC prevention or treatment.¹

Partner Treatment

There is no evidence that treating sexual partners reduces recurrence of VVC.^1,4 Partners do not usually require treatment unless they are symptomatic. Post-coital penile hypersensitivity to vaginal Candida colonisation is possible and may respond to partner treatment in specific cases, but routine partner treatment is not recommended.¹

When to Refer

Most cases of VVC during pregnancy can be handled in primary care or by the obstetric team. Consider referring to a specialist with expertise in vulval medicine if:²

• Symptoms persist despite adequate treatment.
• Diagnosis remains uncertain.
• Recurrent infections (4 or more episodes within 12 months) are poorly controlled.
• Other possible causes, such as dermatitis, lichen sclerosus, herpes simplex, or vulvodynia, should be ruled out.
• Infections caused by non-albicans species may require specialist management.

Special Considerations

First Trimester: Topical imidazole therapy is preferred, with longer courses (seven days) recommended.⁵ Oral fluconazole should be strictly avoided.^1,4,10

Second and Third Trimesters: Continue with topical therapy. There is no evidence that asymptomatic colonisation requires treatment, even in late pregnancy.^5,12

Breastfeeding: Women who are breastfeeding should consult their doctor before starting treatment, as some considerations differ from pregnancy management.^3,4

Patient Counselling Points

When counselling pregnant women with thrush, clinicians should emphasise:^3,4,5

• The infection is very common and does not harm the unborn baby.
• Symptoms can be effectively treated with topical antifungals.
• Longer treatment courses (seven days) are necessary during pregnancy compared to non-pregnant women.
• Oral medications used outside pregnancy are not safe for use during pregnancy.
• Asymptomatic colonisation does not require treatment.
• Preventive measures can help reduce the risk of recurrence.
• Symptoms should improve within a few days of starting treatment.
• If symptoms continue after completing treatment, a medical review is recommended.

Practice Points

Key recommendations for Australian obstetric practice:

• Topical imidazoles are the first-line treatment for symptomatic VVC in pregnancy.^1,2,5
• 7-day courses are more effective than shorter regimens during pregnancy.⁵
• Oral fluconazole is contraindicated throughout pregnancy.^1,4,10
• Asymptomatic colonisation does not require treatment.^1,5,12
• There is no evidence that VVC harms the fetus.⁵
• Partner treatment is not routinely recommended.^1,4
• Self-care measures and avoidance of irritants are recommended.^1,3,4
• Recurrent VVC requires investigation for underlying causes.^1,2

Conclusion

Vulvovaginal candidiasis is a common and often bothersome condition during pregnancy, affecting up to 30% of pregnant women.⁶ Although the infection causes significant discomfort for the mother, evidence consistently shows that it does not harm the fetus.⁵ Treatment differs considerably from that in non-pregnant populations, with a seven-day course of topical imidazole therapy being the main approach.⁵

Australian guidelines emphasise that oral fluconazole is absolutely contraindicated during pregnancy due to teratogenic risks.^1,4,10 Clinicians should focus on effective symptom relief with topical therapy, educate patients on self-care measures, and reassure them about fetal safety. Asymptomatic colonisation does not require treatment, and routine screening is not advised^.1,5,12

For the small proportion of women with recurrent VVC during pregnancy, investigation of underlying causes such as gestational diabetes is necessary, with management involving longer courses of topical treatment under specialist supervision.^1,2 By following evidence-based management aligned with current Australian guidelines, clinicians can effectively manage this common pregnancy complication while ensuring maternal comfort and fetal safety.