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Effects of interventions in pregnancy on maternal weight and obstetric outcomes: meta-analysis of randomised evidence

BMJ 2012; 344 doi: (Published 17 May 2012) Cite this as: BMJ 2012;344:e2088
  1. S Thangaratinam, senior lecturer/consultant in obstetrics and maternal medicine1,
  2. E Rogozińska, researcher1,
  3. K Jolly, reader in public health2,
  4. S Glinkowski, researcher3,
  5. T Roseboom, associate professor45,
  6. J W Tomlinson, MRC senior clinical fellow/reader in endocrinology6,
  7. R Kunz, professor7,
  8. B W Mol, professor5,
  9. A Coomarasamy, professor6,
  10. K S Khan, professor 1
  1. 1Women’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
  2. 2Department of Public Health, Epidemiology and Biostatistics, University of Birmingham, Birmingham
  3. 3Arcana Institute, Krakow, Poland
  4. 4Clinical Epidemiology Biostatistics and Bioinformatics, Academic Medical Centre, Amsterdam, Netherlands
  5. 5Department of Obstetrics and Gynaecology, Academic Medical Centre, Amsterdam
  6. 6School of Clinical and Experimental Medicine, University of Birmingham, Birmingham
  7. 7University of Basel, Basel Institute for Clinical Epidemiology (BICE), Basel, Switzerland
  1. Correspondence to: S Thangaratinam s.thangaratinam{at}
  • Accepted 2 March 2012


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.

Design Systematic review and meta-analysis.

Data sources Major databases from inception to January 2012 without language restrictions.

Study selection Randomised controlled trials that evaluated any dietary or lifestyle interventions with potential to influence maternal weight during pregnancy and outcomes of pregnancy.

Data synthesis 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.


  • Contributors: ST, AC, and KSK developed the protocol with input from other authors. ER and SG performed the search, study selection, and data extraction. ER, SG, and ST analysed the results. ST, AC, and KSK drafted the manuscript. AC and KSK contributed equally to the manuscript. All authors provided input into the development of the manuscript. ST is guarantor.

  • Funding: This study was funded by the National Institute for Health Research (NIHR) HTA (Health Technology Assessment) UK programme 09/27/06. The views and opinions expressed therein are those of the authors and do not necessarily reflect those of the HTA programme, NIHR, NHS, or the Department of Health.

  • Competing interest: All authors have completed the ICMJE uniform disclosure form at (available on request from the corresponding author) and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

  • Ethical approval: Not required.

  • Data sharing: No additional data available.

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