Probiotic ice cream influences gut and vaginal microbiota in women at high risk of preterm birth: a randomized controlled study

BACKGROUND: Research into probiotic use in pregnancy typically focuses on general probiotic strains. We instead investigated the relation between intake of ice cream with vaginal commensal probiotics (L. crispatus, L. gasseri, L. jensenii, L. rhamnosus GR-1; these may govern a stable microbiota and may carry beneficial functions in the vagina), throughout pregnancy, and the impact on gut and vaginal microbiomes, in women at high risk of preterm birth. METHODS: This was a randomised controlled feasibility trial where the impact on gut and vaginal microbiomes was assessed by using 16 S rRNA gene sequencing and qPCR. In total 43 pregnant women were randomized, with 29 assigned to the intervention group and 14 to the control group. Both groups provided vaginal and rectal swabs by self-sampling at gestational time points. Pregnancy outcomes were registered through hospital records, and ice cream adherence and study experience was recorded. RESULTS: We observed statistically significant gut and vaginal Lactobacillus increase during first half of pregnancy in all women with a continued increase in the second half in women compliant with the intervention. L. crispatus was found more often in the intervention group, and L. gasseri, L. jensenii and L. rhamnosus GR-1 in the ice cream could be recovered in both rectal and vaginal samples. Finally, vaginal Prevotella spp, as well as gut Gardnerella and Atopobium spp, significantly decreased upon intervention. Adherence to the intervention varied but gradually decreased throughout the study with 30.4% displaying excellent adherence in the first time period. CONCLUSIONS: We conclude that vaginal commensal probiotics administered in ice cream can be an effective method of optimizing the vaginal and intestinal health in pregnant women at high risk of preterm birth when administered regularly. We give recommendations for future studies. TRIAL REGISTRATION: Clinicaltrials.gov registration number 18/27209. Date of registration 03/25/2019. Date of first enrolment 04/08/2019.