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Study shows link between prenatal antibiotic exposure and allergic diseases

18 July 2022

A review of data from various clinical studies has found that children born to mothers who take antibiotics during pregnancy are at higher risk of developing asthma and other inflammatory or allergic diseases.

Dr Alissa Cait

The findings, published in Allergy, highlight the need to better understand what’s behind this relationship, and the importance of responsible antibiotic stewardship throughout the prenatal period.

“A meta-analysis is an analysis of analyses,” says Malaghan Institute Postdoctoral Fellow Dr Alissa Cait, who led the study. “We synthesised results from 11 prospective and 16 retrospective studies to determine a statistically significant increased likelihood of children developing wheeze, asthma, dermatitis, allergic rhinitis and food allergy if antibiotics were used during pregnancy.

“Importantly, the findings were consistent if antibiotics were prescribed during any trimester, and true of all antibiotic classes except cephalosporins.”

While significant, Dr Cait cautions the findings are only as good as the studies they are built upon and warrant deeper investigation.

“We found that the studies looking at this topic weren't necessarily representative of the wider population, so were difficult to estimate the true effect of these antibiotics. So far all we can see is an interesting correlation – not necessarily causation. They also don’t give us any information on the biological mechanisms behind this relationship. What it does emphasise is the need for in-depth studies in this space.”

As part of the Malaghan Institute’s Gasser Laboratory, Dr Cait and her team have a deep interest in understanding how the immune system and immune health can be influenced by external factors – such as diet, environment and medications.

“We’re interested in understanding the interactions between the microbiome, the products of the microbiome, and how they can influence immune cells. Understanding these interactions will help us explain possible mechanisms we haven’t encountered before, for example, why would intrapartum antibiotic use change the likelihood of childhood asthma?

“There is more and more evidence that the microbiome, particularly in early life, has an important role to play in shaping immune responses later in life, particularly with consequences for allergic disease, so understanding these kinds of mechanisms is really important.”

The over prescription of antibiotics is something that has only recently been closely examined by the scientific community. It is already accepted that over prescribing antibiotics can lead to disease-resistant strains of bacteria, but as this review suggests, Dr Cait believes that it might also have other unintended consequences.

“I think all medical interventions have to be about weighing pros and cons. When we're talking about antibiotics, I’m not sure there has been a lot of consideration or understanding to the con side of the argument. Of course there are going to be times when antibiotics are necessary. But I think the only way to get the balance correct is if we truly understand what the possible side-effects or consequences of antibiotic use are.

“A big part of this is really getting to the bottom of questions like what part of antibiotic use is leading to increased risk of allergic disease? Maybe by understanding the mechanisms behind it we can find interventions and ways to mitigate the increased risk not just during pregnancy, but in other instances, too.”