title: Epigenetic modulation at birth - altered DNA-methylation in white blood cells after Caesarean section.
abstract: OBJECTIVE
  Delivery by C-section (CS) has been associated with increased risk for allergy, diabetes and leukaemia. Whereas the underlying cause is unknown, epigenetic change of the genome has been suggested as a candidate molecular mechanism for perinatal contributions to later disease risk. We hypothesized that mode of delivery affects epigenetic activity in newborn infants.
  
  
  METHODS
  A total of 37 newborn infants were included. Spontaneous vaginal delivery (VD) occurred in 21, and 16 infants were delivered by elective CS. Blood was sampled from the umbilical cord and 3-5 days after birth. DNA-methylation was analyzed in leucocytes.
  
  
  RESULTS
  Infants born by CS exhibited higher DNA-methylation in leucocytes compared with that of those born by VD (p < 0.001). After VD, newborn infants exhibited stable levels of DNA-methylation, as evidenced by comparing cord blood values with those 3-5 days after birth (p = 0.55). On postnatal days 3-5, DNA-methylation had decreased in the CS group (p = 0.01) and was no longer significantly different from that of VD (p = 0.10).
  
  
  CONCLUSIONS
  DNA-methylation is higher in infants delivered by CS than in infants vaginally born. Although currently unknown how gene expression is affected, or whether epigenetic differences related to mode of delivery are long-lasting, our findings open a new area of clinical research with potentially important public health implications.
authors.affiliation: Department of Clinical Science, Intervention and Technology, Karolinska Institute, Stockholm, Sweden.
authors.forename: T
authors.initials: T
authors.lastname: Schlinzig
authors.forename: S
authors.initials: S
authors.lastname: Johansson
authors.forename: A
authors.initials: A
authors.lastname: Gunnar
authors.forename: T J
authors.initials: TJ
authors.lastname: Ekström
authors.forename: M
authors.initials: M
authors.lastname: Norman
mesh_terms: D000328:Adult; D002097:C-Reactive Protein / Q000032:analysis; D002585:Cesarean Section / Q000009:adverse effects*; D019175:DNA Methylation; D036861:Delivery, Obstetric; D044127:Epigenesis, Genetic; D005260:Female; D005312:Fetal Blood / Q000166:cytology; D005492:Folic Acid / Q000032:analysis; D015870:Gene Expression; D006801:Humans; D007231:Infant, Newborn / Q000097:blood*; D007962:Leukocytes; D008297:Male; D012307:Risk Factors; D018709:Statistics, Nonparametric
chemical_list: D002097:C-Reactive Protein; D005492:Folic Acid