title: Effects of interventions in pregnancy on maternal weight and obstetric outcomes: meta-analysis of randomised evidence.
abstract: OBJECTIVE
  To evaluate the effects of dietary and lifestyle interventions in pregnancy on maternal and fetal weight and to quantify the effects of these interventions on obstetric outcomes.
  
  
  METHODS
  Systematic review and meta-analysis.
  
  
  METHODS
  Major databases from inception to January 2012 without language restrictions.
  
  
  METHODS
  Randomised controlled trials that evaluated any dietary or lifestyle interventions with potential to influence maternal weight during pregnancy and outcomes of pregnancy.
  
  
  RESULTS
  Results summarised as relative risks for dichotomous data and mean differences for continuous data.
  
  
  RESULTS
  We identified 44 relevant randomised controlled trials (7278 women) evaluating three categories of interventions: diet, physical activity, and a mixed approach. Overall, there was 1.42 kg reduction (95% confidence interval 0.95 to 1.89 kg) in gestational weight gain with any intervention compared with control. With all interventions combined, there were no significant differences in birth weight (mean difference -50 g, -100 to 0 g) and the incidence of large for gestational age (relative risk 0.85, 0.66 to 1.09) or small for gestational age (1.00, 0.78 to 1.28) babies between the groups, though by itself physical activity was associated with reduced birth weight (mean difference -60 g, -120 to -10 g). Interventions were associated with a reduced the risk of pre-eclampsia (0.74, 0.60 to 0.92) and shoulder dystocia (0.39, 0.22 to 0.70), with no significant effect on other critically important outcomes. Dietary intervention resulted in the largest reduction in maternal gestational weight gain (3.84 kg, 2.45 to 5.22 kg), with improved pregnancy outcomes compared with other interventions. The overall evidence rating was low to very low for important outcomes such as pre-eclampsia, gestational diabetes, gestational hypertension, and preterm delivery.
  
  
  CONCLUSIONS
  Dietary and lifestyle interventions in pregnancy can reduce maternal gestational weight gain and improve outcomes for both mother and baby. Among the interventions, those based on diet are the most effective and are associated with reductions in maternal gestational weight gain and improved obstetric outcomes.
authors.affiliation: Women's Health Research Unit, Centre for Primary Care and Public Health, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK. s.thangaratinam@qmul.ac.uk
authors.forename: S
authors.initials: S
authors.lastname: Thangaratinam
authors.forename: E
authors.initials: E
authors.lastname: Rogozinska
authors.forename: K
authors.initials: K
authors.lastname: Jolly
authors.forename: S
authors.initials: S
authors.lastname: Glinkowski
authors.forename: T
authors.initials: T
authors.lastname: Roseboom
authors.forename: J W
authors.initials: JW
authors.lastname: Tomlinson
authors.forename: R
authors.initials: R
authors.lastname: Kunz
authors.forename: B W
authors.initials: BW
authors.lastname: Mol
authors.forename: A
authors.initials: A
authors.lastname: Coomarasamy
authors.forename: K S
authors.initials: KS
authors.lastname: Khan
mesh_terms: D015992:Body Mass Index; D001835:Body Weight; D016001:Confidence Intervals; D004038:Diet, Reducing; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D009043:Motor Activity; D009765:Obesity / Q000517:prevention & control / Q000628:therapy*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000517:prevention & control / Q000628:therapy*; D011256:Pregnancy Outcome; D047928:Premature Birth / Q000517:prevention & control*; D016032:Randomized Controlled Trials as Topic; D012307:Risk Factors; D040242:Risk Reduction Behavior; D015431:Weight Loss