Study: Antibiotic Use by Mothers Tied to Higher Risk of Disease in Newborns

A new study reveals a mother’s use of antibiotics late in pregnancy or while nursing a newborn can increase the risk of some infants developing inflammatory bowel diseases, particularly among those who are genetically susceptible to such conditions.

“What happens is the antibiotics that the mother receives skews their microbiome and makes it abnormal,” said Dr. Eugene Chang, senior author of the study and professor of medicine at the University of Chicago.

Antibiotics change the composition of the mother’s gut microbiome, depleting it of “essential” microbes (bacteria, viruses, fungi and archaea) necessary for proper immune system development, which is inherited by the infant, explained Chang.

“Everybody thinks antibiotics are harmless,” Chang said. “Antibiotics are very commonly, and unfortunately, injudiciously used, very casually used. ... I think it’s one of many factors that may actually upset this critical period and relationship between the host and microbes that occurs early in life.”

Researchers analyzed the gut microbiomes of adult mice – some of which were treated with antibiotics – and the effect it had on their offspring. What they found was antibiotics caused lasting changes in gut microbiomes of both adult and infant mice, but only the latter developed disease. This suggests the timing of antibiotic exposure is critical.

“Your immune system develops early in life. It is this period of time when the immune system has to be exposed to a full repertoire of stimuli so that it knows eventually what to react against and what not to react against,” said Chang. “It’s teaching our immune system not to react against good microbes that become part of our body and promote health.”

Offspring of mice that were treated with antibiotics were missing “all these microbes that are important for immune education during this critical window of life,” added Chang.

As these mice matured into adulthood, the antibiotic-depleted microbes began regrowing in their microbiomes. Since their bodies weren’t exposed to the microbes during immune system maturation, the body reacted as if they were pathogens and attacked them.

With up to 40 percent of women receiving antibiotics during this time period, Chang said it’s worth rethinking the common practice of prescribing antibiotics when they aren’t warranted.

“There are times when you need antibiotics. They are very, very useful,” he said. “But I think what this study says is that we should use antibiotics judiciously when indicated.”

Physicians often prescribe antibiotics – or patients ask for them – to treat symptoms caused by viruses, like a cold, flu or a sore throat. “Antibiotics have no effect on viruses,” Chang said. “Your own immune system gets over a virus.”

If a woman were to develop a urinary tract infection during the peripartum period, antibiotics would be warranted because most urinary tract infections are caused by bacteria, explained Chang. “Or if the mother or newborn develops bacterial pneumonia, antibiotics are indicated.”

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