A 25-year-old woman who is 16 weeks pregnant with her first child is experiencing increased vaginal discharge associated with vaginal itching. A microscopic examination of the discharge confirms your suspicions of vaginal candidiasis. Is oral fluconazole or a topical azole your treatment of choice?
Because of the increased production of sex hormones, vaginal candidiasis is common during pregnancy, affecting up to 10% of pregnant women in the United States.1,2 Treatment options include oral fluconazole and a variety of topical azoles. Although the latter are recommended as firstline therapy, the ease of oral therapy makes it an attractive option.3,4
However, the safety of oral fluconazole during pregnancy has recently come under scrutiny. Case reports have linked high-dose use with congenital malformation.5,6 These case reports led to epidemiologic studies in which no such association was found.7,8
A large cohort study involving 1,079 fluconazole-exposed pregnancies and 170,453 unexposed pregnancies found no increased risk for congenital malformation or stillbirth; rates of spontaneous abortion and miscarriage were not evaluated.9 A prospective cohort study of 226 pregnant women found no association between fluconazole use during the first trimester and miscarriage.10 However, the validity of both studies’ findings was limited by small numbers of participants.
The current study is the largest to date to evaluate whether use of fluconazole in early pregnancy is associated with increased rates of spontaneous abortion and stillbirth, compared to topical azoles.
Increased risk for miscarriage, but not stillbirth
This nationwide cohort study, conducted using the Medical Birth Register in Denmark, evaluated more than 1.4 million pregnancies occurring from 1997 to 2013 for exposure to oral fluconazole between 7 and 22 weeks’ gestation. Each oral fluconazole–exposed pregnancy was matched with up to four unexposed pregnancies (based on propensity score, maternal age, calendar year, and gestational age) and to pregnancies exposed to intravaginal formulations of topical azoles. Exposure to fluconazole was documented by filled prescriptions from the National Prescription Register. Primary outcomes were rates of spontaneous abortion (loss before 22 weeks) and stillbirth (loss after 23 weeks).
Rates of spontaneous abortion. Of the total cohort, 3,315 pregnancies were exposed to oral fluconazole between 7 and 22 weeks’ gestation. Spontaneous abortion occurred in 147 of these pregnancies and in 563 of 13,246 unexposed, matched pregnancies (hazard ratio [HR], 1.48).
Rates of stillbirth. Of 5,382 pregnancies exposed to fluconazole from week 7 to birth, 21 resulted in stillbirth; 77 stillbirths occurred in the 21,506 unexposed matched pregnancies (HR, 1.32). In a sensitivity analysis, however, higher doses of fluconazole (350 mg) were four times more likely than lower doses (150 mg) to be associated with stillbirth (HRs, 4.10 and 0.99, respectively).
Oral fluconazole vs topical azole. Use of oral fluconazole in pregnancy was associated with an increased risk for spontaneous abortion, compared to topical azole use (130 of 2,823 pregnancies vs 118 of 2,823 pregnancies; HR, 1.62)—but not an increased risk for stillbirth (20 of 4,301 pregnancies vs 22 of 4,301 pregnancies; HR, 1.18).