How to Avoid Gestational Diabetes

Gestational diabetes is high blood sugar that first develops during pregnancy, usually in the third trimester.

Gestational diabetes is bad because it can lead to babies being large for gestational age (which causes birth complications such as need for C-sections).  It can also cause problems in neonates if untreated: hypoglycemia, jaundice, respiratory distress syndrome, and other chemical imbalances.  Women who have gestational diabetes are at risk for later developing Type II diabetes — 9.6x greater than women who didn’t get gestational diabetes.[2] Usually gestational diabetes can be treated with diet (low-carb or low-glycemic-index) and/or medications like insulin and metformin.

Risk Factors

Maternal Age > 40. Older mothers have an odds ratio of 7.0 for gestational diabetes.[1]

Obesity. Prepregnancy BMI > 35 is associated with an odds ratio of 6.1 for gestational diabetes.[1]  Prepregnancy BMI > 25 is associated with an odds ratio of 4.14.[3]

Being Asian. White women are the least likely to have gestational diabetes, while Asian women are the most: a study of 11205 women attending a clinic in the UK found that Asian women were 8-18x as likely as white women to get gestational diabetes.[5]  The highest rates of gestational diabetes in the world are found among the Pima Indians.[5]  In a NYC clinic, a retrospective study of 329,988 births found that the prevalence of gestational diabetes in Asians was 2.5x that in whites.[6]

Lack of Exercise.  Women who exercised at all in the year before pregnancy had 0.44x the risk of gestational diabetes of women who didn’t, and women who exercised at least 4.2 hrs/week had 0.24x the risk of sedentary women.[4]


Treating gestational diabetes helps prevent bad outcomes!  Compared to placebo, a “treatment program” consisting of dietary modification, glucose monitoring, and insulin as necessary, resulted in fewer large-for-gestational age infants (7.1% vs 14.5%), less shoulder dystocia (1.5% vs 4.0% — this is when the baby’s shoulder gets stuck in the birth canal during delivery), and fewer C-sections (26.9% vs 33.8%).[7]  A different study found no effect on C-section rates but a significant drop in perinatal complications in the treatment group (1% vs 4%.).  A meta-analysis of relevant studies found that treatment significantly reduced the incidence of large for gestational age infants and shoulder dystocia, but didn’t significantly reduce C-sections or perinatal mortality.[9]

Bottom Line

To a first approximation (which is all I’m going to do), gestational diabetes is pretty straightforward. “Eat healthy and exercise.”


[1]Teh, Wan T., et al. “Risk factors for gestational diabetes mellitus: implications for the application of screening guidelines.” Australian and New Zealand Journal of Obstetrics and Gynaecology 51.1 (2011): 26-30.

[2]Lee, Anna J., et al. “Gestational diabetes mellitus: Clinical predictors and long-term risk of developing type 2 diabetes a retrospective cohort study using survival analysis.” Diabetes care 30.4 (2007): 878-883.

[3]Cypryk, Katarzyna, et al. “Gestational diabetes mellitus-an analysis of risk factors.” Endokrynol Pol 59.5 (2008): 393-7.

[4]Dempsey, Jennifer C., et al. “Prospective study of gestational diabetes mellitus risk in relation to maternal recreational physical activity before and during pregnancy.” American journal of epidemiology 159.7 (2004): 663-670.

[5]Reece, E. Albert, Gustavo Leguizamón, and Arnon Wiznitzer. “Gestational diabetes: the need for a common ground.” The Lancet 373.9677 (2009): 1789-1797.

[6]Rosenberg, Terry J., et al. “Maternal obesity and diabetes as risk factors for adverse pregnancy outcomes: differences among 4 racial/ethnic groups.”American journal of public health 95.9 (2005): 1545-1551.

[7]Landon, Mark B., et al. “A multicenter, randomized trial of treatment for mild gestational diabetes.” New England Journal of Medicine 361.14 (2009): 1339-1348.

[8]Crowther, Caroline A., et al. “Effect of treatment of gestational diabetes mellitus on pregnancy outcomes.” New England Journal of Medicine 352.24 (2005): 2477-2486.

[9]Horvath, Karl, et al. “Effects of treatment in women with gestational diabetes mellitus: systematic review and meta-analysis.” Bmj 340 (2010): c1395.