When a baby is the womb, their gut is completely sterile (free from bacteria). At birth, they begin taking in bacteria, which rapidly develops within the gut. Until now, it was assumed that the bacteria in babies’ guts was introduced by bacteria from the mother’s birth canal.
This new study has demonstrated that babies born vaginally pick up most of their first dose of bacteria from their mother. However, babies born by c-section (caesarean) have more bacteria linked to hospital environments. This could explain why instances of asthma, allergies and other immune conditions in babies born by c-section are higher.
Experts are clear that these findings should not alarm women who were planning to have, or have had, a c-section.
“This important study confirms that the way we give birth will alter our microbiome in the first year of life. Caesarean delivery results in fewer bacteria in the baby’s gut being like its mother’s […] This is not known to be harmful and mothers who need a caesarean should not be alarmed. The further effects of this in long term health need to be evaluated.”
Professor Andrew Shennan, Professor of Obstetrics and Tommy’s Clinical Director at Guy’s and St Thomas’ Hospital.
Researchers took faecal samples from nearly 600 babies and 175 mothers. This study is the most comprehensive study to date of the process of microbiome development in babies. The study also showed that the antibiotics given before a c-section and breastfeeding also have an impact on babies’ gut bacteria.
“In many cases, a caesarean is a life-saving procedure and can be the right choice for a woman and her baby. The exact role of the microbiome in the newborn and what factors can change it are still uncertain, so we don’t think this study should deter women from having a caesarean.”
Alison Wright, a consultant obstetrician and vice-president of the Royal College of Obstetricians and Gynaecologists.
If you have any concerns about this information or about having a c-section, we have more information on our website.
You can read more in about the study here.