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Adherence to healthy lifestyle and risk of gestational diabetes mellitus: prospective cohort study

BMJ 2014; 349 doi: (Published 30 September 2014) Cite this as: BMJ 2014;349:g5450
  1. Cuilin Zhang, investigator1,
  2. Deirdre K Tobias, research fellow2,
  3. Jorge E Chavarro, assistant professor23,
  4. Wei Bao, postdoctoral fellow1,
  5. Dong Wang, research fellow2,
  6. Sylvia H Ley, research fellow2,
  7. Frank B Hu, professor23
  1. 1Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20852, USA
  2. 2Departments of Nutrition and Epidemiology, Harvard School of Public Health, Boston, MA 02115, USA
  3. 3Channing Division of Network Medicine, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA 02115, USA
  1. Correspondence to: C Zhang zhangcu{at}
  • Accepted 18 August 2014


Objective To quantify the association between a combination of healthy lifestyle factors before pregnancy (healthy body weight, healthy diet, regular exercise, and not smoking) and the risk of gestational diabetes.

Design Prospective cohort study.

Setting Nurses’ Health Study II, United States.

Participants 20 136 singleton live births in 14 437 women without chronic disease.

Main outcome measure Self reported incident gestational diabetes diagnosed by a physician, validated by medical records in a previous study.

Results Incident first time gestational diabetes was reported in 823 pregnancies. Each lifestyle factor measured was independently and significantly associated with risk of gestational diabetes. The combination of three low risk factors (non-smoker, ≥150 minutes a week of moderate to vigorous physical activity, and healthy eating (top two fifths of Alternate Healthy Eating Index-2010 adherence score)) was associated with a 41% lower risk of gestational diabetes compared with all other pregnancies (relative risk 0.59, 95% confidence interval 0.48 to 0.71). Addition of body mass index (BMI) <25 before pregnancy (giving a combination of four low risk factors) was associated with a 52% lower risk of gestational diabetes compared with all other pregnancies (relative risk 0.48, 0.38 to 0.61). Compared with pregnancies in women who did not meet any of the low risk lifestyle factors, those meeting all four criteria had an 83% lower risk of gestational diabetes (relative risk 0.17, 0.12 to 0.25). The population attributable risk percentage of the four risk factors in combination (smoking, inactivity, overweight, and poor diet) was 47.5% (95% confidence interval 35.6% to 56.6%). A similar population attributable risk percentage (49.2%) was observed when the distributions of the four low risk factors from the US National Health and Nutrition Examination Survey (2007-10) data were applied to the calculation.

Conclusions Adherence to a low risk lifestyle before pregnancy is associated with a low risk of gestational diabetes and could be an effective strategy for the prevention of gestational diabetes.


  • Contributors: CZ designed the study. FH was involved in data collection. DKT and DW provided statistical expertise. DKT and DW analyzed the data. CZ wrote the first draft of the manuscript. All authors contributed to the interpretation of the results and revision of the manuscript for important intellectual content and approved the final version of the manuscript. CZ and FH are guarantors.

  • Funding: This study was supported by the intramural research program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health (contract No HHSN275201000020C). The Nurses’ Health Study II was funded by research grants DK58845, CA50385, P30 DK46200, and UM1 CA176726 from the National Institutes of Health and by an American Diabetes Association Award 7-12-MN-34.

  • Competing interest: All authors have completed the ICMJE uniform disclosure form at and declare: no support from any organization for the submitted work; no financial relationships with any organizations 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: The study protocol was approved by the institutional review boards of the Partners Health Care System (Boston, MA, USA). The completion of the self administered questionnaire was considered to imply informed consent.

  • Transparency declaration: The lead author, CZ, affirms that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted.

  • Data sharing: No additional data available.

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