The relationship between an ­unborn baby and its mother’s placenta is indivisible, I’ve ­always thought. But research suggests something can come ­between them: the mother’s gut bacteria.

Indeed, her gut microbes could help in the development of the placenta and with the healthy growth of her baby, the University of East Anglia, the Quadram Institute and University of Cambridge have discovered.

Microbes in our gut, collectively called the gut microbiome, are known to play a key role in maintaining health by combating infections, influencing our immune system and metabolism.

Researchers found a species of gut bacteria that changes the mother’s body during pregnancy, affecting the structure of the placenta and how it transports nutrients – both factors that aid the growing baby.

The bacterium, Bifidobacterium breve, is widely used as a probiotic, so this could lead to ways of combating pregnancy complications, ensuring a healthy start in life. But how?

To address this question, the team analysed how Bifidobacterium breve ­supplements affected pregnancy in mice. Yes, I know, mice. But ­interesting. Professor Lindsay Hall, from UEA, has been studying Bifidobacterium and the microbiome in very early life, previously having shown how providing specific probiotics can help premature babies.

Prof Hall said: “Our findings reveal that the maternal microbiome promotes development of the placenta and growth of the foetus. Excitingly it appears that adding in a probiotic ­Bifidobacterium during pregnancy may help to boost how the placenta functions, which has positive effects on the baby’s growth in utero.”

In this study they also looked at the effect of feeding germ-free mice – which were lacking any microbes – the probiotic and compared them to mice with normal microbiomes. In germ-free mice, the foetus didn’t receive adequate sugar and failed to grow and develop properly. Excitingly, providing Bifidobacterium breve to them helped the foetus by restoring foetal metabolism, growth and normal development.

Researchers also found the microbiome promoted the transport of sugars within the placenta, aiding the growth of the foetus.

These findings are strong indicators of a link between the microbiome of the mother and the development of the baby. More studies are needed and it can’t be immediately translated into treatment for humans.

But it’s proof of a concept. And it could provide a simple, low-cost way to improve pregnancy outcomes with positive benefits for the life-long health of mother and child.

“The placenta has been a neglected organ, despite it being vital for the growth and survival of the foetus, said Dr Jorge Lopez-Tello, from Cambridge University. “A better understanding of how the placenta grows and functions will ultimately result in healthier pregnancies for mothers and babies.”