According to a new study published in Nature Microbiology, babies born via Caesarean section (C-section) are likely to fail to respond to one dose of the live attenuated MMR (measles, mumps, rubella) vaccine. In fact, researchers found it is 2.6 times more likely that the vaccine is ineffective for babies, who are born via C-section, than babies who are born vaginally.1 2 3
The study by researchers at the University of Cambridge and Fudan University in China concluded that the immune systems of C-section babies do not produce a robust response to the initial dose of the MMR vaccine. It is hypothesized that the gut microbiome of C-section babies is not as developed as that of vaginally born babies and, therefore, the babies do not produce an adequate immune response to the vaccine.4 According to previous studies, babies born vaginally receive more genetically diverse gut-colonizing microbes from their mothers, which boosts their immune response.5
Henrik Salje, co-senior study author said:
We’ve discovered that the way we’re born—either by C-section or natural birth—has long-term consequences on our immunity to diseases as we grow up.6
Researchers examined data of 1,505 children in the first year of life from 2013 through 2018 finding that 12 percent of babies born via C-section failed to mount an immune response to the measles shot compared to only five percent of vaginally born children.7 8
The research, funded by the National Natural Science Foundation of China, looked at a mother-neonate cohort and a population-based cohort of children one to nine years old. Researchers followed up on the infant cohort approximately every six months from 2013 to 2016. Researchers looked at blood samples of the infants over time to determine how measles antibody levels changed over time, including pre and post vaccination..9 10
The study showed that a second dose of the MMR vaccine produced a more robust immune response in babies born via C-section.11
The implications of the first dose of the MMR vaccine being less effective in babies born by c-section are vast as approximately one-third of all pregnant women in the United States and the United Kingdom end up having C-sections. In Brazil and Turkey, more than one half of all children are born by C-section.12 13
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