Results
A total of 281 neonates were enrolled in the study, consisting of 139
and 142 neonates in the vaginal delivery group (VG) and the cesarean
section group (CS), respectively. Three cases from the VG group were
excluded due to inability to provide a fecal sample within 48 hours, and
two cases from the CS group were excluded due to preterm delivery, after
a review of data. The mean fecal collection times were 18.6 (12.1) hours
and 21.0 (14.8) hours in the VG and CS groups, respectively.
The sequencing successfully identified the microbial taxonomy of the gut
in 89 (64.0%) samples of the VG group and 44 (31.43%) samples of the
CS group. We used only these data for statistical analysis. The
demographic data of the patients is presented in Table 1. Overall, the
mean maternal age was 27.9 (5.1) years old. There were significantly
higher levels of income, education status, and underlying maternal
disease in the CS group. All mothers consumed all types of food except
three cases in the CS group with seafood allergies.
The 16S rRNA sequencing results revealed higher total gut microbiome
reads in the VG group (7,019,452) than in the CS group (3,359,444). Of
those reads, 6,897,967 (98.27%) and 3,299,355 (98.21%) were classified
as microbiomes in the VG and CS groups, respectively. The diversity of
the neonates’ gut microbiomes was greater in those born via vaginal
delivery than those born via cesarean delivery. Of the species
identified in this study, 17 (51.5%) were found exclusively in the VG
group, while nine (27.3%) were found exclusively in the CS group. Only
seven species (21.2%) were found in both groups (Figure 3).
Bifidobacterium was the dominant genus in both the VG group and the CS
group. The proportion of Bifidobacterium was significantly higher in the
CS group (Table 2). Among all the Bifidobacterium species identified,Bifidobacterium breve was the most dominant, followed byBifidobacterium longum. In the 89 samples of the VG group, 24
bacteria species were found with a relative abundance percentage of more
than 0.5%, and in the 44 samples of the CS group, 16 bacteria species
were found with a relative abundance percentage of more than 0.5%.
(Figure 4). A significantly higher abundance of Bifidobacterium,
Enterobacter, and Enterococcus species was found in the CS group
compared to the VG group (Table 2).
In the VG group, Clostridium (6.9%), Enterococcus (5.5%), Escherichia
(4.5%), and Streptococcus (4.4%) were found to be the second most
abundant genera in fecal specimens. Some, such as the genera
Fusobacterium, Streptococcus, Bacteroides, Megamonas, and Escherichia,
were found exclusively in the VG group. In the CS group, the most
abundant genera after Bifidobacterium were Enterobacter (11.2%),
Lactobacillus (7.8%), Enterococcus (7.2%), and Klebsiella (4.6%).
However, opportunistic pathogens such as Enterococcus, Klebsiella, and
Clostridium were found in both groups.
In the CS group, there was no significant difference in neonatal gut
microbiome abundancy between those presenting with labor and those
presenting without labor before cesarean delivery (Table 3).