A Dutch study has confirmed that although antibiotics given to mothers who will undergo a cesarean section can cause slight changes in the friendly microbes that live with infants, their effect is much less than the effect of the way the children are fed.
Reassuring results for mothers
Mothers who are going to have a cesarean section are usually given prophylactic antibiotics just before the operation to prevent infection at the surgical site later. But there have been concerns about whether these antibiotics could negatively affect newborns and their natural microbes (microbiome) if the drugs travel through the umbilical cord and reach the baby before it is cut.
“We decided to do this study because it addresses an important clinical question that could have profound implications for infant health,” says Trishla Sinha, the study’s first author from the University Medical Center Groningen in the Netherlands. “It is important to balance high-quality evidence showing immediate benefits for the mother with equally strong evidence about any potential short- and long-term risks to the infant. Mothers often ask whether the antibiotics they take affect their babies, and this study can provide reassurance that they only have small effects on the gut microbiome in babies.”
The study that answers the big question
Some previous studies have looked at this question, but they were conducted with smaller numbers of participants. The first part of the current study included 28 mother-infant pairs. Twelve of the mothers received antibiotics before the skin incision, while the other 16 received antibiotics after the umbilical cord was cut. 172 samples of the infants’ gut microbiome were collected at eight different time points after birth, up to one year. The second part of the analysis also included data from two similar trials for a total of 79 infants.
The researchers examined the samples they collected to see what types of gut microbiome the infants had, their strain diversity, and the composition of antibiotic resistance genes. They also looked at the composition of bile acids and short-chain fatty acids. In addition to information about antibiotic use, the researchers had information about whether the infants were formula-fed or breastfed.
The role of nutrition
The results of this study, published on August 14 in the journal Cell Host & Microbe, showed that the method of feeding had a significant effect on the diversity of microbes in the gut, the composition and types of bacteria, as well as the formation of bile acids that facilitate the digestion of fats.
Formula-fed infants had a significantly different microbiome profile, with feeding method explaining 12% of the variance in overall gut microbiome composition during the first 6 weeks of life. These differences were also reflected in the fecal bile acid profiles of these infants.
Recent research has suggested that the gut microbiome and bile acids play a vital role in the development of immune disorders later in life. Therefore, these early life changes could have important long-term effects. Long-term studies are needed to confirm these findings.
“We were surprised that antibiotics did not significantly alter the microbiome, because other research has suggested that antibiotics have a significant impact on the composition of the gut microbiome in infants,” Sinha says, according to EurekAlert. “This may be due to the fact that it is a single dose of intravenous antibiotics during birth versus prolonged exposure to antibiotics throughout infancy.”
Future studies
In their next study, the researchers plan to examine a cohort of 1,500 mother-infant pairs, looking at various health, environmental and dietary factors during pregnancy and birth, as well as postnatal factors that may influence the composition of the infants’ gut microbiome. The researchers plan to follow the children throughout childhood and into adulthood to assess the long-term effects of the gut microbiome on future health outcomes.
“It is also important to recognize that changes in the gut microbiome do not immediately translate into future health outcomes for the child,” Sinha says. “These issues still need to be studied more thoroughly in longitudinal studies with longer follow-up.”