Researchers in Iran studied 274 pregnant women to understand how different eating patterns affect gestational diabetes—a type of diabetes that develops during pregnancy. They found that women who followed a heart-healthy eating plan called DASH (which emphasizes vegetables, fruits, and whole grains) had a lower risk of developing gestational diabetes. Similarly, women who ate fewer foods that cause inflammation in the body also had lower risk. This suggests that what pregnant women eat in the year before pregnancy might help protect them from this common pregnancy complication.

The Quick Take

  • What they studied: Whether eating patterns that reduce body inflammation and following a healthy DASH diet can lower the chances of developing gestational diabetes during pregnancy
  • Who participated: 274 Iranian pregnant women—138 who had developed gestational diabetes and 136 who had healthy pregnancies. Average age was about 30 years old.
  • Key finding: Women who followed the DASH diet most closely had about 64% lower risk of gestational diabetes. Women who ate the least inflammatory foods had about 48% lower risk compared to those eating the most inflammatory foods.
  • What it means for you: If you’re planning to become pregnant, eating more vegetables, fruits, whole grains, and lean proteins while limiting processed foods and sugary items may help reduce your gestational diabetes risk. However, this study shows association, not proof of cause-and-effect, so talk with your doctor about personalized nutrition advice.

The Research Details

This was a case-control study, which means researchers compared two groups of women: those who developed gestational diabetes and those who didn’t. They looked back at what these women ate during the year before they became pregnant using a detailed food questionnaire with 147 different foods. Researchers then calculated two diet scores for each woman: one measuring how inflammatory their diet was, and another measuring how closely they followed the DASH diet pattern. The DASH diet emphasizes vegetables, fruits, whole grains, lean proteins, and low-fat dairy while limiting salt, sugar, and saturated fats.

All women were tested for gestational diabetes between 24-28 weeks of pregnancy using a standard glucose tolerance test. This test involves drinking a sugary liquid and measuring how the body processes it. Researchers then compared the eating patterns of women who developed gestational diabetes with those who didn’t, while accounting for other factors like age and lifestyle.

Case-control studies are useful for studying pregnancy complications because they let researchers look back at eating habits before pregnancy developed. This approach helps identify dietary patterns that might protect against gestational diabetes. Understanding which foods and eating patterns reduce risk is important because gestational diabetes affects many pregnant women and can lead to health problems for both mother and baby.

This study has several strengths: it used a detailed food questionnaire to capture eating habits, it adjusted for multiple factors that could affect results, and it studied a specific population in Iran where gestational diabetes is common. However, the study relied on women remembering what they ate a year earlier, which can be inaccurate. The study was also conducted in one region of Iran, so results may not apply equally to all populations. The sample size of 274 women is moderate—larger studies would provide stronger evidence.

What the Results Show

Women who most closely followed the DASH diet had significantly lower gestational diabetes risk. Specifically, women in the highest DASH diet group had about 64% lower risk compared to those in the lowest group. This difference was statistically significant, meaning it’s unlikely to have happened by chance.

Women who ate the least inflammatory diet also showed protection. Those eating the least inflammatory foods had about 48% lower risk compared to those eating the most inflammatory foods. Inflammation in the body is thought to play a role in developing gestational diabetes, so reducing inflammatory foods may help prevent it.

Both findings remained true even after researchers accounted for other factors like age, weight, physical activity, and family history of diabetes. This suggests the diet patterns themselves were important, not just these other factors.

The study measured specific components of the DASH diet and inflammatory markers. The DASH diet’s emphasis on whole grains, vegetables, fruits, and lean proteins appeared particularly protective. Foods that increase inflammation—like processed meats, refined grains, and sugary items—were associated with higher gestational diabetes risk. The study also showed that these diet patterns were more important than any single food, suggesting overall eating patterns matter more than individual food choices.

Previous research has shown that the DASH diet helps prevent type 2 diabetes and heart disease in the general population. This study extends that finding to gestational diabetes in pregnant women. The connection between diet-related inflammation and gestational diabetes is newer research, and this study adds to growing evidence that inflammation plays a role in pregnancy complications. However, most previous studies on this topic have been conducted in Western countries, so this Iranian study helps confirm findings apply to different populations.

The main limitation is that women reported what they ate a year before pregnancy from memory, which can be inaccurate. The study only included women from one city in Iran, so results may not apply to all populations or countries. The study design shows association between diet and gestational diabetes but cannot prove that diet directly causes the difference in risk—other unmeasured factors could be involved. Additionally, the study didn’t measure actual inflammation markers in the blood, only estimated inflammation based on food intake. Larger studies following women over time would provide stronger evidence.

The Bottom Line

If you’re planning pregnancy or currently pregnant, consider adopting a DASH-style eating pattern that emphasizes vegetables, fruits, whole grains, lean proteins, and low-fat dairy while limiting processed foods, added sugars, and salt. This approach appears to reduce gestational diabetes risk based on moderate-quality evidence. Discuss specific dietary changes with your healthcare provider or a registered dietitian who can personalize recommendations for your situation. These recommendations are most relevant for women at risk for gestational diabetes.

This research is most relevant for women planning pregnancy, those with family history of diabetes, women with overweight or obesity, and those from populations with higher gestational diabetes rates. Women already diagnosed with gestational diabetes should follow their doctor’s specific meal plan. This research may be less directly applicable to women at very low risk for gestational diabetes, though healthy eating benefits everyone.

Dietary changes work best when started before pregnancy or early in pregnancy. The protective effects likely develop over months of consistent healthy eating rather than overnight. Most women should expect to see benefits in blood sugar control within 2-4 weeks of dietary changes, though gestational diabetes prevention may take longer to demonstrate.

Want to Apply This Research?

  • Track daily servings of vegetables (goal: 3-4), fruits (goal: 2-3), whole grains (goal: 3-4), and lean proteins (goal: 2-3) to monitor DASH diet adherence. Also track processed foods and added sugars consumed to monitor inflammatory food intake.
  • Start by replacing one refined grain per day with a whole grain option (like brown rice instead of white rice), adding one extra vegetable serving to lunch or dinner, and reducing one processed food or sugary drink. Build these changes gradually over 2-3 weeks.
  • Weekly check-ins on diet adherence using the app’s food logging feature. Monthly review of DASH diet score and inflammatory food patterns. If pregnant, coordinate with healthcare provider’s glucose monitoring schedule to track any changes in blood sugar levels.

This research suggests an association between diet patterns and gestational diabetes risk but does not prove cause-and-effect. Gestational diabetes is a complex condition influenced by genetics, weight, age, and other factors beyond diet. If you are pregnant or planning pregnancy, consult with your healthcare provider or registered dietitian before making significant dietary changes. This information is not a substitute for medical advice, diagnosis, or treatment. All pregnant women should be screened for gestational diabetes as recommended by their healthcare provider, regardless of diet.