From the time they are born, babies are given a "starter pack" of bacteria from their mum that is vital for their future health.

Nearly 60 percent of a baby's microbiome in their first 30 days of life is inherited from their mum, according to a new study of 120 Dutch mothers and their babies.

This seeding of essential communities of microbes occurs in babies that are vaginally born as well as those born via a caesarean section.

While caesarean babies got less of their mum's gut and vaginal microbes, they received more of their microbiome through breastmilk than vaginally born babies.

The study was the first to track multiple colonies of microbes in both mothers and babies.

Along with the gut, which is most often studied, other parts of the body such as the skin and respiratory system are home to billions of microscopic flora.

“We wanted to have a better idea of how the infant microbiome develops in different parts of their bodies and how it's influenced by factors such as birth mode, antibiotic use, and lack of breastfeeding,” Dr de Steenhuijsen Piters said.

Building a microbiome

To trace the development of an infant's microbial community over time, the researchers took samples from the babies' skin, nose, saliva, and gut two hours after they were born, and again when they were aged one day, one week, two weeks, and one month.

They also took samples from the mums' skin, breastmilk, nose, throat, faecal matter, and vagina.

The study found that different parts of the mother's microbial communities seeded different parts of the infant's microbiome.

While it was unclear which specific microbes were delivered via breastmilk, Dr de Steenhuijsen Piters said the finding suggests there are alternative and compensatory routes to seed the microbiomes of babies that missed out on gut and vaginal flora when they were born.

"It helps to get breastmilk microbes that push the gut microbiome out in the right direction,"

"But we can't say whether giving breastmilk will fully compensate for the lack of gut/vaginal microbes."

Even if a mum couldn't breastfeed, which was common, essential microbes could be acquired from other sources such as from the mum's skin or respiratory tract.

"There are so many sources there, and likely there's overlap."

Three years to play with

Emad El-Omar, director of the UNSW Microbiome Research Centre, said the study offered reassurance to mums who had given birth by caesarean section.

"The most important message coming out of it would be the compensation that occurs despite of the mode of delivery,"

"I always get asked this question, 'I've had a caesarean section. Is my baby doomed?' That's not the case at all."

"There's plenty of stuff you can do to protect that baby for the future."

The first three years between birth and toddlerhood are thought to be critical for the development of the microbiome.

And while the starter kit in the first month was important, Professor El-Omar said there was still potential to build a healthy microbiome when babies go onto solids.

"We should really be paying a lot of attention to what we feed our babies and children moving forward," he said.

"You've got three years to try and get the most healthy and diverse [microbiome]."

Reference:
^{ABC - https://www.abc.net.au/news/health/2023-03-09/babies-microbiome-mothers-birth-caesarean-section/102059396}