QotW: How do c-section babies get their gut microbes?

Everyone has gut bacteria that keep them healthy. How do babies get them if they're born by caesarian section?
21 April 2020


Baby's feet



On one of the Naked Scientists programmes it was mentioned that a newborn baby has initially sterile intestines and gets most of its microbiome during the passage through the uterus and vagina. What happens to children that are brought into this world via caesarean?


Pavel sent in this question - and Adam Murphy delivered an answer...

Adam - The microbiome is the collection of bacteria that exist in, and on you. It’s an ecosystem in its own right, and issues with a person’s microbiome have been linked to a litany of diseases. So it’s important, if we can, to put the best foot forward. So what happens to the microbiome during a caesarean section? We reached out to Peter Brocklehurst from the University of Birmingham.

Peter - It depends on whether the waters around the baby are intact or broken at the time of the caesarean section. If the caesarean section is done after the waters around the baby have broken, whether this is in labour or before labour starts, then bacteria from the mother's vagina can reach the baby and be present in the baby's gut at the time of the caesarean section. We believe that the longer the waters are broken, the more likely the varieties of bacteria in these babies will resemble those of a baby born vaginally.

Adam - When the mother’s water breaks, the fluid filled sac in the womb, called amniotic sac, ruptures, and usually happens at the start of labour, but not always with a ceasarean section

Peter - Babies born by caesarean section with the waters intact, which is more than half of all births by caesarean section, pick up bacteria from the environment. This can include the mother's skin, the midwives hands, any instruments used after the birth – such as oxygen masks if the baby needs help breathing – and other hospital surfaces that the baby, or anyone handling the baby, may come into contact with. Our research showed that babies born by caesarean section with intact waters were much more likely to have bacteria in their guts which are found in hospitals, and some of these potentially harmful bacteria were resistant to antibiotics.

Adam - There are many reasons a mother may choose to have a caesarean section, both personal and medical. These reasons are totally valid but given our continually growing understanding of the importance of the microbiome, it’s worth understanding what happens at all stages of life.

Peter - We don’t yet know what this means for babies in the long term. Once babies start feeding and being exposed to all sorts of other bacteria as they get older, the types of bacteria babies have in their guts changes and becomes more similar, but even after 6 months we still found more potentially harmful antibiotic-resistant bacteria in the guts of babies born by caesarean section.

Adam - Thank you Peter, for doing the labour in bringing us that answer, next week, we look into this question, which has been getting on Matt’s nerves.

Matt - Do all humans have the same number of nerve endings on their skin? And if so do those of us who are bigger, either taller or fatter, have the same sensitivity of a given area of skin reduced?


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