Faecal transplants for caesarean babies? Screen them first for dangerous bugs

Babies born via caesarean section don’t get as much exposure to their mothers’ gut microbiome, which has led to fears they might be more vulnerable to immune-related diseases.

To combat this doctors have tried vaginal seeding – swabbing the baby with its mother’s vaginal fluids – and even faecal transplants from mothers.

But a trial being carried out by Finnish scientists is making it clear that mothers should be carefully screened before doing a faecal transplant: nearly half of the mothers in their study had potentially very harmful pathogens in their poo.

The researchers are running the randomised trial at Helsinki University Hospital, to investigate whether faecal transplants can improve the health of C-section born children.

They’ve presented interim results at the European Congress of Clinical Microbiology & Infectious Diseases (ECCMID) annual meeting.

Since the trial’s start in 2019, they’ve recruited 90 healthy pregnant people who were scheduled for elective C-sections.

Each participant donates a small amount of their poo for the transplant, which is screened for dangerous pathogens.

Then, within two hours of birth, their newborns are either given 3.5 milligrams of the transplant, or a placebo, mixed in with breast milk.

But so far, 38 (42%) of the participants haven’t made it past screening. Their faecal microbiomes have included bacteria like group B Streptococcus and Helicobacter pylori, or parasites like Dientamoeba fragilis: all of which can cause severe infections in newborns.

“The high rate of significant pathogens found in healthy mothers underscores that this procedure should be only performed after careful screening,” says Dr Otto Helve, a researcher at Helsinki University Hospital and the Finnish Institute of Health and Welfare.

“Healthy people typically carry low levels of harmful bacteria in and on their bodies. But when a person is healthy, these pathogens don’t cause disease; they simply coexist in an abundance of beneficial microbes. However, some, like group B Streptococcus can cause life-threatening infection in the newborn.”

The researchers will be following the newborns for their first two years of life, checking immunological changes and taking stool and blood samples to see if the transplants make a difference.

Research published last month suggested that caesarean-born babies still made up microbial diversity from other sources, so more work needs to be done to see if these transplants are worth the effort.

“So far, 31 babies have received the transplant or placebo without any noticeable side effects, and in May 2023 we will begin assessing whether FMT can enrich the gut microbiota of C-section babies to match that of those vaginally born,” says Helve.