IBD and pregnancy: importance of vaginal microbiota

Inflammatory bowel disease (IBD), which includes Crohn’s disease and ulcerative colitis, is frequently diagnosed in women of childbearing age and increases the risk of premature delivery, caesarean section, and low birth weight. While pregnancy in healthy women changes the composition of the vaginal microbiota, there is no evidence that this change occurs in women suffering from IBD. A new study has investigated this important period.

Pregnancy: enigma of the vaginal microbiota 

Numerous studies have highlighted the gut microbiota’s role in IBD. The role of the vaginal microbiota, however, is not yet known. Nor is it known whether pregnancy modifies the vaginal microbiota composition of women suffering from IBD, as has been observed in healthy pregnant women, whose vaginal microbiota becomes more stable, less rich and less diversified, and displays a greater abundance of lactobacilli (sidenote: Lactobacilli Rod-shaped bacteria whose main characteristic is the production of lactic acid, from where they get the name “lactic acid bacteria”.  Lactobacilli are present in the oral, vaginal and gut microbiota of humans, but also in plants and animals. They are found in fermented foods, such as dairy products (e.g. certain cheeses and yoghurts), pickles, sauerkraut, etc. Lactobacilli are also found in probiotics, with certain species recognized for their beneficial properties.   W. H. Holzapfel et B. J. Wood, The Genera of Lactic Acid Bacteria, 2, Springer-Verlag, 1st ed. 1995 (2012), 411 p. « The genus Lactobacillus par W. P. Hammes, R. F. Vogel Tannock GW. A special fondness for lactobacilli. Appl Environ Microbiol. 2004 Jun;70(6):3189-94. Smith TJ, Rigassio-Radler D, Denmark R, et al. Effect of Lactobacillus rhamnosus LGG® and Bifidobacterium animalis ssp. lactis BB-12® on health-related quality of life in college students affected by upper respiratory infections. Br J Nutr. 2013 Jun;109(11):1999-2007. ) .

Solving the equation, IBD + pregnancy + vaginal microbiota 

To solve this equation, which includes several unknowns, Canadian researchers studied the vaginal microbiota composition of 32 pregnant women suffering from IBD, obtaining samples from them during each trimester. By the end of the study, nearly 44% of the women had delivered at term by cesarean section, while two had delivered prematurely.

The researchers observed that the composition of their vaginal microbiota remained stable throughout pregnancy and was dominated by lactobacilli. However, bacterial species of the class Mollicutes – some of whose species are associated with preterm birth – were identified in 80% of the IBD patients at least once during pregnancy, a rate significantly higher than that observed in 172 healthy pregnant women who delivered at term.