By Dani Cooper, ABC Science
Bacteria critical to early immunity development in infants may be partially restored in babies born by caesarean section by swabbing them with their mother’s birth fluid, a new study suggests.
The small pilot study, published today in Nature Medicine, aimed to address concerns that children born by C-section rather than vaginally have an increased risk of obesity, asthma, allergies and immune deficiencies.
Co-author of the study, Assistant Professor Jose Clemente, from the Icahn School of Medicine at Mount Sinai, said previous studies had found drastic differences in the microbiome in vaginally delivered and C-section infants.
"While the first are enriched in vaginal bacteria from the mum, the latter [those delivered by C-section] completely miss those bacteria," Dr Clemente said.
This was important because the microbiome that colonised the body of newborns helped the baby's immune system learn which were helpful and disease-causing bacteria, he said.
The human microbiome is the set of bacterial species that live on and in human skin, mouths and guts. It has evolved over millions of years to play roles in human digestion, metabolism and immunity.
Dr Clement said there were studies in mice that showed if you modified their microbes early in life there were clear consequences later in life.
"In humans this has still not been demonstrated, so our study is a first step in that direction: if we reintroduce the microbes a C-section infant lacks, can we lower the risk of these diseases?" he asked.
However, Dr Clemente said while their latest work showed the microbes could be partially restored, the study was too small to make any claims about health outcomes.
Small study compared bacteria in first month of life
For the study the researchers collected samples from 18 infants and their mothers, including seven born vaginally and 11 delivered by scheduled C-section.
Four of the C-section babies were swabbed within two minutes of birth with a sterile gauze that had been incubated in the mother's vagina during the hour before the procedure.
A total of 1,519 samples were obtained from anal, oral and skin sites of infants and mothers at six time points during the first month of life.
These showed the microbiomes of the four C-section-delivered infants exposed to vaginal fluids resembled those of vaginally delivered infants, particularly during the first week of life.
Importantly those swabbed at birth had similar levels of Lactobacillus and Bacteroides, species shown by past studies to train the infant's immune system to recognise and not attack helpful bacteria (immune tolerance).
But the procedure did not transfer all of the microbes seen in vaginally born infants.
The researchers believe the partial microbiota restoration may be due to the way the bacteria was transferred via the gauze and also the effects of antibiotic treatments on the mothers before surgery.
Dr Clemente said the researchers were now recruiting a larger cohort, which would allow them to better track the changes in the babies' microbiome during the first month.
"Once this is determined then we can move into biological and clinical questions that will be much more interesting: do health outcomes change by using this procedure? Do they work for everybody, and if not what determines who benefits and who doesn't?"
Benefits if technique is proven to work
He said the swabbing technique used in the study was non-invasive but very simplistic.
If further studies could show that restoring the microbiome of infants after C-sections improves health outcomes, Dr Clements said he was "sure the procedure to transfer the bacteria will evolve into something very different".
"The way a doctor vaccinates a child now is very different to how this was done back in the 18th century, and so the same will happen with our approach to restore microbes," he said.
Dr Clemente said the finding was important because C-section rates were soaring worldwide.
"However, even if you reduce C-sections to the recommended 15 per cent of cases when it is medically required to protect the life of the mother or the infant ... that is 30,000 children in Australia or 400,000 in the US, every year," he said.
"If we can restore the potential benefits of vaginal delivery to all those children, you get the best of both scenarios: a safe birthing without the side effects of starting life with the wrong bacteria."
This post originally appeared on the ABC.