Cesarean Section Strongly Impacts Stool Microbiota of Bangladeshi Infants in Low-income Settings

The delivery by Cesarean section (CS) is becoming increasingly common, including in middle-income settings. CS has been linked to later in life (infancy and childhood) health problems, including increased susceptibility to infections and chronic immune disorders. Infant gut microbiota has been hypothesized to play a key role in these outcomes.

We set out to examine the impact of delivery mode on initial stool microbiota of infants from periurban community in Bangladesh, Dhaka. The delivery mode was decided jointly by the family and the obstetrician independently of the participation in the study. Stool samples were collected from 263 infants between the day of birth and day 3. The composition of stool microbiota was evaluated by 16S rRNA gene sequencing.

67 out of 263 infants (26%) were delivered by CS. The CS rate was similar among primiparous women (30/107, 28%), and women who had already given birth before (37/156, 24%). Notably, only 4 out of 156 women (2.6%) delivered by CS in their previous pregnancy (delivery on average 5 years before).

CS had a clear impact on stool microbiota. The stool microbiota of CS delivered infants was dominated by Klebsiella (37%) and other Enterobacteriaceae (17%) while vaginally delivered (VD) infants harbored mostly Escherichia (58%) and less Klebsiella (10%). In VD infants, on the day of birth, the relative abundance of Escherichia was 32% and increased to 78% on day 3. In CS delivered infants, Escherichia was absent until day 1, and reached 23% only on day 3.

We have observed a ten-fold increase in CS rate from 2.6% to 24% over a time span of 5 years in a periurban community in Dhaka, Bangladesh. The usual process of gut colonization appears to be delayed after CS. To better understand the long-term impact of the delivery mode on infant microbiota and associated infant health outcomes, the health of infants in this cohort will be monitored for the first 2 years of life.