Cesarean delivery may result in lower bacterial diversity, lower abundance of the phylum Bacteroidetes, and lower circulating levels of Th1 chemokines in infants compared with vaginal delivery, according to a study published online August 7 in Gut. Lower diversity may lead to higher exposure to health risks such as allergies later in life.
Hedvig E. Jakobsson, MSc, from the KTH Royal Institute of Technology and Karolinska Institutet, Stockholm, Sweden, and colleagues followed-up 24 infants born by healthy women, 15 by vaginal delivery and 9 by cesarean delivery, from birth through age 24 months. The women and children were part of a larger study on prevention of allergies by probiotics, and 20 (83%) of the babies were partly breast-fed up until 6 months of age.
The researchers analyzed stool samples collected from the mothers 1 week after delivery and from the infants at 1 week and 1, 3, 6, 12, and 24 months after delivery. They compared microbial gene sequences isolated from mother and infant stool samples. They also collected venous blood samples from the infants at 6, 12, and 24 months of age. None of the infants received antibiotics, and any mothers who received antibiotics did so only after birth.
Although microbiota developed in a similar fashion at the phylum level for infants in both delivery-method groups, the researchers found that vaginal delivery infants had significantly higher proportions of Bacteroidetes than cesarean delivery infants, particularly at 1 week, 3 months, and 12 months. They also found moderately lower levels of Th1-associated chemokines in blood samples from cesarean delivery infants, which could increase risk for immune-mediated diseases such as allergy, diabetes, and inflammatory bowel disease.
This study comes only a few months after another study found that cesarean delivery, combined with lack of breast feeding, may negatively influence gut bacteria development and lead to health risks later in life.
“[Cesarean delivery] was associated with a lower diversity of the Bacteroidetes phylum when considering all time points (p=0.002),” the authors of the current study write.
“Our study corroborates earlier studies reporting a delayed colonization of Bacteroides in babies delivered by [cesarean delivery].” In addition, they write, the new gene sequencing data indicate that “specific lineages of the intestinal microbiota, as defined by 16S rRNA gene sequences, are transmitted from mother to child during vaginal delivery.”
The researchers point out that more knowledge of how delivery mode affects microbiota composition and building of immunity may lead to improved allergy prevention strategies.