title: Mode of delivery - effects on gut microbiota and humoral immunity.
abstract: BACKGROUND
  The rate of caesarean deliveries has increased 10-fold worldwide during the past decades.
  
  
  OBJECTIVE
  To evaluate differences in the establishment of gut microbiota in infants born by vaginal or caesarean delivery and its impact on mucosal immunity.
  
  
  METHODS
  Altogether, 165 consecutive children, prospectively followed from birth at our clinic in Turku, Finland, were gathered; 141 (85%) were born by vaginal delivery and 24 (15%) by caesarean section. Blood was drawn at physician visits for indirect evaluation of mucosal immunity by ELISPOT assay. Faecal samples were obtained for determination of the gut microbiota by fluorescence in situ hybridization of bacterial cells.
  
  
  RESULTS
  Infants delivered by caesarean section harboured fewer bifidobacteria at an early age and were shown to mount a stronger humoral immune response. At 1 month of age, the total gut bacterial cell counts per 1 g faeces were higher in vaginally delivered infants (9.9 x 10(9), 95% CI 7.9 x 10(9)-1.2 x 10(10)) as compared to caesarean section delivered (3.1 x 10(9), 95% CI 1.1 x 10(9)-8.6 x 10(9)) (p = 0.001). This distinction was mainly due to the greater number of bifidobacteria in vaginally delivered infants (1.9 x 10(9), 95% CI 6.3 x 10(8)-5.6 x 10(9) vs. 1.5 x 10(6), 95% CI 4.1 x 10(2)-5.7 x 10(9), respectively) (p = 0.001). During the first year of life, the total number of IgA-, IgG- and IgM-secreting cells was lower (p = 0.03, p = 0.02, p = 0.11, respectively) in infants born by vaginal delivery than in those born by caesarean section, possibly reflecting excessive antigen exposure across the vulnerable gut barrier.
  
  
  CONCLUSIONS
  Our findings demonstrate that the mode of delivery may have, possibly via gut microbiota development, significant effects on immunological functions in the infant (http://www.clinicaltrials.gov/ct/gui/show/NCT00167700).
authors.affiliation: Department of Pediatrics, Turku University Central Hospital and University of Turku, Turku, Finland. anu.huurre@utu.fi
authors.forename: Anu
authors.initials: A
authors.lastname: Huurre
authors.forename: Marko
authors.initials: M
authors.lastname: Kalliomäki
authors.forename: Samuli
authors.initials: S
authors.lastname: Rautava
authors.forename: Minna
authors.initials: M
authors.lastname: Rinne
authors.forename: Seppo
authors.initials: S
authors.lastname: Salminen
authors.forename: Erika
authors.initials: E
authors.lastname: Isolauri
mesh_terms: D000328:Adult; D000917:Antibody Formation / Q000276:immunology*; D001644:Bifidobacterium / Q000254:growth & development / Q000302:isolation & purification*; D002585:Cesarean Section; D036861:Delivery, Obstetric; D005243:Feces / Q000382:microbiology*; D005260:Female; D005865:Gestational Age; D006801:Humans; D007223:Infant; D007413:Intestinal Mucosa / Q000382:microbiology; D007422:Intestines / Q000382:microbiology*; D011247:Pregnancy; D011446:Prospective Studies