Baby gut study finds bacteria different after C-section births
A huge study of babies' stool samples has found key differences between
infants born vaginally and via Caesarean section, offering clues about the
development of the human immune system, researchers said on Wednesday.
Vaginally born babies got most of their gut bacteria from their mother, but
C-section babies did not and had more bacteria linked to the hospital around
them, the study found.
It is not clear what impact the difference may have on children's future
health, and the findings should not deter women from having C-section births,
the scientists leading the work said.
But the so-called "baby biome" project - the world's largest such
study - had opened a window on a little-understood stage in the development of
human immunity, they added.
"The first weeks of life are a critical window of development of the
baby's immune system, but we know very little about it," said Peter
Brocklehurst, a Birmingham University professor who co-led the study.
"We need to follow up ... these babies as they grow to see if early
differences in the microbiome lead to any health issues."
The gut microbiome is a complex ecosystem of millions of microbes and is
thought by scientists to be important for how the immune system develops.
Previous research has suggested that a lack of exposure to some microbes in
early life is implicated in autoimmune diseases such as asthma, allergies and
diabetes.
But scientists have not yet been able to work out how important the initial
gut microbiome - or "baby biome" - is to future immunity and health,
or how a baby's microbiome develops, or what happens to it with different modes
of birth.
In this research, published in the journal Nature, scientists from
University College London, Wellcome Sanger Institute and Birmingham University
used DNA sequencing to analyse more than 1,600 gut bacteria samples from 175
mothers and almost 600 babies.
In samples from mothers and from the babies at four, seven and 21 days old,
the team found there was a significant difference between the two delivery
methods - with vaginally delivered babies having many more health-associated
bacteria from their mothers than babies born by Caesarean.
In place of some of the mother's bacteria, the C-section babies had more
bacteria typically found in hospitals, the researchers said, and these bugs
were also more likely to be drug-resistant.
"At the moment we don't understand the long-term consequences of
this," Brocklehurst said at a briefing about the results. "It's
clearly complex and we're only just beginning to scratch the surface."