What role does bacteria play in a delivery?

Children born by caesarean section have a different bacterial flora. Researcher Emma Fransson and her colleagues at the Centre for Translational Microbiome Research (CTMR) are now studying whether this can be restored, thereby reducing the risk of allergies.

Picture of Emma Fransson in front of Aula Medica
Emma Fransson, CTMR. Photo: Pernilla Sjöholm

How does a caesarean section affect the bacterial flora?

“Previous studies have shown that children delivered by caesarean are colonised by more skin bacteria and hospital bacteria compared to children delivered vaginally, who receive more bacteria from the mother’s vagina and gut in their microbiota.”

What impact does this have on health?

“We know from large register studies that children born by caesarean have an increased risk of developing asthma and allergies, as well as other diseases such as diabetes. In part, this may be explained by the child having too little of certain bacteria and that this affects their immune system, which needs to be challenged in order to develop. For certain diagnoses, it may be difficult to identify a causal relationship, given that caesareans are more common among women with various types of health problems.”

Are these differences in bacterial flora permanent?

“Although it does appear that the bacterial flora in caesarean-born children normalises over the first few months of life, studies are needed. Other factors such as antibiotics, breastfeeding, pets and number of siblings may also affect the bacterial flora after birth.”

What is the RoMaNs study?

“RoMaNs stands for Restoration of Microbiota in Newborns, a multicentre study coordinated by CTMR at Karolinska Institutet but being conducted at five hospitals around the country. The purpose is to establish whether children delivered by caesarean section who are immediately rubbed with the mother’s vaginal and gut microflora then develop a bacterial flora similar to that of vaginally delivered babies. We will also be examining whether this treatment can reduce the risk of developing allergies. The study has started and we will be recruiting a total of 330 women.”

What method will you be using?

“Children born to healthy women by planned caesarean section will be randomly selected for active treatment or placebo, with children delivered virginally included as a control group. When the child is born, samples of bacterial flora will be taken from the skin (mother and child), breastmilk and the child’s faeces. The same samples will be taken at one month, six months, 12 months and 24 months. We will also take blood samples to study the development of the immune system, as well as looking at incidence of atopic eczema and allergies.”

Why is your study necessary?

“A few minor studies have attempted to restore bacterial flora using the mother’s vaginal flora but we have added gut microflora. Our study, which is larger than those previously published, will also examine the development of the immune system and whether we can reduce the risk of the child developing allergies. Many women who give birth by caesarean section are keen to give the baby their own bacteria but the lack of clinical trials means that healthcare providers are unable to offer this. If the treatment proves to be effective, we hope that is will be possible to offer it to all children delivered by caesarean section.” 

Text: Felicia Lindberg, first published in Swedish in the magazine Medicinsk Vetenskap No 3/2020. 

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