Cited by 262Gestational Diabetes Research and ManagementPregnancy and Medication ImpactBirth, Development, and Health

Effect of metformin on maternal and fetal outcomes in obese pregnant women (EMPOWaR): a randomised, double-blind, placebo-controlled trial

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Chiswick, Carolyn, Reynolds, Rebecca M, Denison, Fiona, Drake, Amanda J, Forbes, Shareen, Newby, David E, Walker, Brian R, Quenby, Siobhan +7 more·2015·The Lancet Diabetes & Endocrinology

Abstract

BACKGROUND: Maternal obesity is associated with increased birthweight, and obesity and premature mortality in adult offspring. The mechanism by which maternal obesity leads to these outcomes is not well understood, but maternal hyperglycaemia and insulin resistance are both implicated. We aimed to establish whether the insulin sensitising drug metformin improves maternal and fetal outcomes in obese pregnant women without diabetes. METHODS: We did this randomised, double-blind, placebo-controlled trial in antenatal clinics at 15 National Health Service hospitals in the UK. Pregnant women (aged ≥16 years) between 12 and 16 weeks' gestation who had a BMI of 30 kg/m(2) or more and normal glucose tolerance were randomly assigned (1:1), via a web-based computer-generated block randomisation procedure (block size of two to four), to receive oral metformin 500 mg (increasing to a maximum of 2500 mg) or matched placebo daily from between 12 and 16 weeks' gestation until delivery of the baby. Randomisation was stratified by study site and BMI band (30-39 vs ≥40 kg/m(2)). Participants, caregivers, and study personnel were masked to treatment assignment. The primary outcome was Z score corresponding to the gestational age, parity, and sex-standardised birthweight percentile of liveborn babies delivered at 24 weeks or more of gestation. We did analysis by modified intention to treat. This trial is registered, ISRCTN number 51279843. FINDINGS: Between Feb 3, 2011, and Jan 16, 2014, inclusive, we randomly assigned 449 women to either placebo (n=223) or metformin (n=226), of whom 434 (97%) were included in the final modified intention-to-treat analysis. Mean birthweight at delivery was 3463 g (SD 660) in the placebo group and 3462 g (548) in the metformin group. The estimated effect size of metformin on the primary outcome was non-significant (adjusted mean difference -0·029, 95% CI -0·217 to 0·158; p=0·7597). The difference in the number of women reporting the combined adverse outcome of miscarriage, termination of pregnancy, stillbirth, or neonatal death in the metformin group (n=7) versus the placebo group (n=2) was not significant (odds ratio 3·60, 95% CI 0·74-17·50; p=0·11). INTERPRETATION: Metformin has no significant effect on birthweight percentile in obese pregnant women. Further follow-up of babies born to mothers in the EMPOWaR study will identify longer-term outcomes of metformin in this population; in the meantime, metformin should not be used to improve pregnancy outcomes in obese women without diabetes. FUNDING: The Efficacy and Mechanism Evaluation (EME) Programme, a Medical Research Council and National Institute for Health Research partnership.

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Authors
Chiswick, C., Reynolds, R. M., Denison, F., Drake, A. J., Forbes, S., Newby, D. E., Walker, B. R., Quenby, S., Wray, S., Weeks, A., Lashen, H., Rodriguez, A., Murray, G., Whyte, S., & Norman, J. E.
Affiliations
  • MRC Centre for Reproductive Health (GB)
  • British Heart Foundation Centre for Cardiovascular Science (GB)
  • Edinburgh Royal Infirmary (GB)
  • University of Warwick (GB)
  • Liverpool Women's Hospital (GB)
  • Jessop Hospital (GB)
  • University of Edinburgh (GB)
Corresponding author
Norman, Jane E
Venue
The Lancet Diabetes & Endocrinology
Publisher
Elsevier BV
Published
2015-10
Volume
3
Issue
10
Pages
778-786
ISSN
2213-8587 (ISSN-L)
OpenAlex
W2144199745
Cited by
260
References
36
Citations by year
2026: 12 · 2025: 20 · 2024: 15 · 2023: 21 · 2022: 21 · 2021: 27 · 2020: 28 · 2019: 28 · 2018: 33 · 2017: 22 · 2016: 27 · 2015: 6
FWCI
33.38
Type
journal article
Language
en
Open access
Locations
  • The Lancet Diabetes & Endocrinology (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • Explore Bristol Research (publishedVersion)
  • Warwick Research Archive Portal (University of Warwick) (acceptedVersion)
  • Edinburgh Research Explorer (University of Edinburgh) (submittedVersion, cc-by)
  • Bristol Research (University of Bristol) (submittedVersion, cc-by)
  • Newcastle University ePrints (Newcastle Univesity)
Funders
  • Wellcome Trust (103782)
  • National Institute for Health and Care Research (08/246/09)
  • Medical Research Council (MC_G1002463)
Topics
  • Health Sciences › Medicine › Obstetrics and Gynecology › Gestational Diabetes Research and Management
  • Health Sciences › Medicine › Public Health, Environmental and Occupational Health › Pregnancy and Medication Impact
  • Health Sciences › Medicine › Pediatrics, Perinatology and Child Health › Birth, Development, and Health
Keywords
metformin, maternal obesity, pregnancy, birth weight, insulin resistance, miscarriage, stillbirth, preterm birth, gestational diabetes mellitus, maternal hyperglycemia, placental growth factor, placental insufficiency, fetal growth restriction, placental DNA methylation, epigenetics
MeSH terms
Abortion, Spontaneous, Adult, Double-Blind Method, Female, Fetal Macrosomia, Humans, Hypoglycemic Agents, Metformin, Pregnancy, Pregnancy Complications, Pregnancy Outcome, Diabetes, Gestational, Stillbirth, Young Adult, Obesity, Abdominal

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