The randomized, double-blind, placebo-controlled, parallel-arm study, which included 180 healthy women in the third trimester of pregnancy, used Lallemand’s Prenatis-branded combination of Lactobacillus rhamnosus Rosell-11 and Bifidobacterium bifidum HA-132.
In addition to the probiotics contributing to lower rates of infections for the mothers, the benefits of the probiotics extended to the babies, with significantly fewer sick days reported.
Maternal probiotic supplementation was also associated with positive effects on gut microbiome establishment in the infants, particularly in those delivered by C-section due to the vertical transmission from mother to baby, according to the findings published in Nutrients.
“We are very proud to announce the publication of this study, which involved a large cohort of healthy pregnant women and included follow-up of their babies up to one year of age,” said Sylvie Binda, one of the paper’s lead authors and vice president of research and development at Lallemand Health Solutions.
“This research is innovative, and we worked closely with experts to deepen our understanding of vertical microbial transfer in the establishment of the infant’s microbiome. We also gained new insights into pregnancy, particularly during the third trimester.”
Study details
Pregnant women are reported to have a higher susceptibility to certain viral, bacterial and fungal infections, and pregnancy can exacerbate those infections. The researcher sought to investigate if probiotic supplementation during pregnancy confers any immune health benefits to mother and child.
The study randomly assigned 180 pregnant women to receive either placebo or the Prenatis combination of L. rhamnosus and B. bifidum (total 5 billion CFUs per day) for the final 12 weeks of their third trimester. Supplementation then continued for four to six weeks after birth. Mothers and their children were followed for one year.
The results showed that women in the probiotic group had a reduction in the incidence of both bacterial and fungal infections. Additionally, significantly fewer women taking probiotics were diagnosed with infections during the study period compared to placebo.
“While there was a trend for the reduction in the number of infections in the probiotics group, the significant reduction in the proportion of women presenting infections over the course of the study supports the idea that probiotics were broadly effective and that their benefits were not only experienced by a subset of intervention responders,” the researchers reported.
“This is an interesting finding from a clinical perspective, considering the study’s main objective to test a supplement that confers protection against infections during the last trimester of pregnancy. Women who received probiotics tended to be less susceptible to bacterial vaginosis (BV), the most commonly observed infection, compared to those in the placebo group.”
The babies also benefited from the probiotic supplementation, with shorter durations of infections and greater gut colonization by beneficial bacteria like Bifidobacteria, particularly in infants delivered by C-section.
“Since they lack exposure to the mother’s vaginal microbiota and may require additional support to initiate healthy microbiome establishment, infants born by C-section may benefit from probiotic intake in mothers during pregnancy and lactation to a larger extent than infants born vaginally,” the researchers wrote.
Source: Nutrients, 2025, 17(11), 1825. doi: 10.3390/nu17111825. “The Effect of Probiotics on Health in Pregnancy and Infants: A Randomized, Double-Blind, Placebo-Controlled Trial”. Authors: S. Binda, et al.