Cesarean section is sometimes the preferred or safer method of infant delivery, depending on individual circumstances. There is one downfall to the procedure, however; it can deprive infants of beneficial microbiota that they would otherwise be exposed to with vaginal delivery. But in a new study, researchers may have come up with a simple solution to this problem: swabbing newborns with their mother's vaginal birth fluid.

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Researchers say their study shows it is feasible to partially restore beneficial bacteria lost through C-section by swabbing newborns with their mother's vaginal birth fluid.

Lead study author Maria Dominguez-Bello, PhD, an associate professor in the Department of Medicine at NYU Langone Medical Center in New York, NY, and colleagues publish the details of their novel idea in the journal Nature Medicine.

The World Health Organization (WHO) recommend that no more than 10-15% of births should be by cesarean section (C-section). In the US, however, C-section rates stand at 32.2%, increasing almost seven-fold since the mid-1960s.

A C-section is primarily done as a result of foreseen or unexpected problems during delivery, though some mothers elect for the procedure over vaginal delivery.

While C-section can be a life-saving operation in some circumstances, numerous studies have linked the procedure to greater risk of negative health outcomes for the infant, such as increased risk of obesity and asthma.

Researchers have suggested that these increased risks are down to lack of exposure to the mother's vaginal microbiome with C-section delivery. This is spurred by the finding that the microbiomes of children born by C-section differ from those of vaginally delivered infants, with the latter holding bacterial communities that more closely resemble those of the mother's vagina.

Only a few animal studies have demonstrated a direct link between microbial differences between vaginal and C-section delivery and risk of disease. However, researchers have pointed to a correlation between an increase in microbial-disrupting factors among infants - such as C-section and antibiotic use in pregnancy - and an increase in rates of asthma, obesity and autoimmune diseases in recent decades.

"With a third of US babies now born by C-section, twice the number as is medically necessary, the question of whether a baby's founding microbiome affects its future disease risk has become more urgent," says Dominguez-Bello.

Vaginal fluid restored bacteria key for immune system development

For their study, the team set out to determine whether applying a mother's vaginal fluid to their baby shortly after birth may influence their microbial composition.

The researchers enrolled seven pregnant women who were expected to deliver their baby vaginally, alongside 11 expectant mothers who had scheduled C-section.

Fast facts about C-section
  • C-section is the most common procedure performed in operating rooms across the US
  • In 1965, the C-section rate in the US was 4.5%
  • US C-section rates peaked in 2009, at 32.9%.

Learn more about C-section

Four of the scheduled C-section mothers agreed to have a vaginal swab using an incubated sterile gauze 1 hour before delivery. Within 2 minutes of giving birth, the gauze was used to swab their newborn's mouth, face and body.

During the 30 days after birth, the researchers took over 1,500 samples from various body sites of all participating mothers and their infants. The team applied DNA sequencing and big data analytics to these samples in order to characterize the microbial communities of babies delivered vaginally and by C-section.

Compared with the C-section infants who were not swabbed with their mother's vaginal fluid after birth, the team found that those who were had microbial communities that more closely resembled those of babies who were delivered vaginally.

Specifically, the researchers found that both the vaginally delivered infants and the C-section babies who were swabbed with their mother's vaginal fluid had similarly higher levels of Lactobacillus and Bacteroides shortly after birth, compared with C-section infants who were not exposed to their mother's vaginal fluid.

The team notes that previous studies have shown that Lactobacillus and Bacteroides are bacterial species that aid immune tolerance in infants, effectively training a baby's immune system to avoid attacking beneficial bacteria.

While the researchers admit that their study sample was small, they say the findings show that partial restoration of microbial communities shortly after birth is feasible for babies born by C-section.

Whether the procedure is likely to yield any health benefits for C-section infants, however, is a question that warrants further investigation.

Dominguez-Bello says:

"Larger studies that measure the effect of early microbiome restoration on health outcomes would begin to answer whether or not it averts future disease risk.

The current study represents proof of a principle in a small cohort, and shows that our method is worthy of further development as we seek to determine the health impact of microbial differences."

In June 2015, Medical News Today reported on a study that suggested massaging the umbilical cord of infants delivered by C-section may offer significant benefits, such as improved blood pressure, increased levels of red blood cells and better blood flow.