title: Probiotics for preventing gestational diabetes.
abstract: BACKGROUND
  Gestational diabetes mellitus (GDM) is associated with a range of adverse pregnancy outcomes for mother and infant. The prevention of GDM using lifestyle interventions has proven difficult. The gut microbiome (the composite of bacteria present in the intestines) influences host inflammatory pathways, glucose and lipid metabolism and, in other settings, alteration of the gut microbiome has been shown to impact on these host responses. Probiotics are one way of altering the gut microbiome but little is known about their use in influencing the metabolic environment of pregnancy.
  
  
  OBJECTIVE
  To assess the effects of probiotic supplementation when compared with other methods for the prevention of GDM.
  
  
  METHODS
  We searched the Cochrane Pregnancy and childbirth Group's Trials Register (31 August 2013) and reference lists of the articles of retrieved studies.
  
  
  METHODS
  Randomised and cluster-randomised trials comparing the use of probiotic supplementation with other methods for the prevention of the development of GDM. Cluster-randomised trials were eligible for inclusion but none were identified. Quasi-randomised and cross-over design studies are not eligible for inclusion in this review. Studies presented only as abstracts with no subsequent full report of study results would also have been excluded.
  
  
  METHODS
  Two review authors independently assessed study eligibility, extracted data and assessed risk of bias of included study. Data were checked for accuracy.
  
  
  RESULTS
  Eleven reports (relating to five possible trials) were found. We included one study (six trial reports) involving 256 women. Four other studies are ongoing.The included trial consisted of three treatment arms: probiotic with dietary intervention, placebo and dietary intervention, and dietary intervention alone; it was at a low risk of bias. The study reported primary outcomes of a reduction in the rate of gestational diabetes mellitus (risk ratio (RR) 0.38, 95% confidence interval (CI) 0.20 to 0.70), with no statistical difference in the rates of miscarriage/intrauterine fetal death (IUFD)/stillbirth/neonatal death (RR 2.00, 95% CI 0.35 to 11.35). Secondary outcomes reported were a reduction in infant birthweight (mean difference (MD) -127.71 g, 95% CI -251.37 to -4.06) in the probiotic group and no clear evidence of increased risk of preterm delivery (RR 3.27, 95% CI 0.44 to 24.43), or caesarean section rate (RR 1.23, 95% CI 0.65 to 2.32). The primary infant outcomes of rates of macrosomia and large-for-gestational age infants were not reported. The following secondary outcomes were not reported: maternal gestational weight gain, pre-eclampsia, and the long-term diagnosis of diabetes mellitus; infant body composition, shoulder dystocia, admission to neonatal intensive care, jaundice, hypoglycaemia and long-term rates of obesity and diabetes mellitus.
  
  
  CONCLUSIONS
  One trial has shown a reduction in the rate of GDM when women are randomised to probiotics early in pregnancy but more uncertain evidence of any effect on miscarriage/IUFD/stillbirth/neonatal death. There are no data on macrosomia. At this time, there are insufficient studies to perform a quantitative meta-analysis. Further results are awaited from four ongoing studies.
authors.affiliation: Internal Medicine, Royal Brisbane and Women's Hospital, Butterfield Street, Herston, Queensland, Australia, 4029.
authors.forename: Helen L
authors.initials: HL
authors.lastname: Barrett
authors.forename: Marloes
authors.initials: M
authors.lastname: Dekker Nitert
authors.forename: Louise S
authors.initials: LS
authors.lastname: Conwell
authors.forename: Leonie K
authors.initials: LK
authors.lastname: Callaway
mesh_terms: D016640:Diabetes, Gestational / Q000517:prevention & control*; D005260:Female; D006801:Humans; D011247:Pregnancy; D019936:Probiotics / Q000627:therapeutic use*; D016032:Randomized Controlled Trials as Topic