Pregnancy causes many hormonal changes that help support the pregnancy. These changes affect metabolism and the way your body uses and stores food and can increase the risk of developing high blood sugar and diabetes during pregnancy. Diabetes that develops during pregnancy is called gestational diabetes and is a type of metabolic dysfunction, a disruption in your body's ability to turn food into energy. Here we discuss why the right amount of blood sugar is important, what changes take place during pregnancy, and strategies to help regulate blood sugar in pregnancy.1
What is blood sugar?
The term “blood sugar” refers to the amount of glucose that circulates in the blood. Glucose is a sugar which is an important source of fuel for cells throughout the body. When starchy or sweet foods are consumed, the carbohydrates that they are made of are broken down into single glucose molecules. These molecules circulate in the blood until they are taken up by cells to be used for energy or stored for later. When metabolic function is normal, the body controls the amount of sugar in the blood by making insulin, a hormone which helps muscles and cells take up glucose from the blood. In metabolic dysfunction, the cells of the body cannot take up enough glucose, leaving more of it circulating in the blood. Too much glucose in the blood can cause damage to cells and organs.
What happens to blood sugar during pregnancy?
In pregnancy, two things happen that change metabolism and increase the amount of glucose in the blood.
1) The placenta makes hormones (e.g., human placental lactogen, estrogen, progesterone, etc.) that make it more difficult for cells to respond to insulin and take up glucose from the blood. A decreased ability of the body’s cells to respond to insulin is called "insulin resistance."
2) Most pregnant people need to increase the amount of food they consume to meet energy and nutrient needs to support the growth of their baby. This increase in food intake, along with pregnancy-related insulin resistance, makes it harder for the body to control the amount of glucose in the blood.1
Why does managing blood sugar matter?
Managing blood sugar during pregnancy can help keep both mom and baby healthy. Healthy lifestyle choices, such as food choices and exercise, can help prevent high blood sugar. This is important because even mildly elevated blood sugar during pregnancy has been linked to the development of health issues for both mothers and their babies.2 Babies born to mothers with elevated blood sugar during pregnancy are at increased risk for macrosomia (weighing more than 8 lb 13 oz at birth) and truncal asymmetry (where the baby's shoulder and trunk are larger than normal).3 These conditions increase the rate of need for surgical birth, maternal trauma, significant vaginal tears, and neonatal fractures.4
The risk of elevated blood sugar in pregnancy is higher if you had excess weight before pregnancy, a previous diagnosis of gestational diabetes, or a family history of diabetes. But there are ways to stay metabolically healthy during pregnancy. This includes choosing a healthy and nutritious diet and staying physically active (after checking with your doctor!) throughout pregnancy.
What is a healthy and nutritious diet in pregnancy?
Focusing on foods that are nourishing during pregnancy will support health throughout pregnancy and can reduce risk of complications.
1. Eat whole, unprocessed, fiber-rich foods – This means eating less processed foods and more high-fiber foods such as vegetables, fruits, whole grains, and legumes.
- Eat the rainbow! [Red (tomatoes, strawberries, apples); Orange (carrots, peppers, oranges); Yellow (lentils, bananas); Green (broccoli, peas, leafy greens, green apples); Blue (berries); Purple (eggplant).]
- While fresh fruits and vegetables have distinct health benefits, eating frozen and canned vegetables are an excellent alternative to preprepared foods or fast food.
- The daily fiber recommendation is 28 to 36 g. Foods that are high in fiber take longer to digest and raise your blood sugar more slowly.5 Some examples of such foods include oats, brown rice, nuts, seeds, and beans.
2. Consider your protein intake – Protein is an important building block to support growth! The USDA recommends that 30% of calories come from protein, and a minimum of about 71g during pregnancy.6,7
- Good sources of protein include: lean meats, chicken, eggs, certain fish, soy (tofu), and beans.
- Two to three weekly servings, totalling 8-12 ounces per week, of certain fish such as anchovies, canned light tuna, catfish, mussels, farmed or wild salmon, or trout are great for the baby's development providing essential nutrients and protein.8,9
- However, avoid fish with high levels of mercury such as bigeye tuna, king marckerel, marlin, and swordfish.9
- This CDC site provides more information on safe fish options in pregnancy.
3. Carbohydrates are the primary nutrient affecting blood glucose – The amount, type, and timing of carbohydrate intake directly influence changes in blood sugar.10
- How much? – A daily mimimum of 175 g of carbohydrate and 28 g of fiber is required for most pregnant women.11 It is recommended that carbs make up between 45 to 65% of the calories in your diet during pregnancy.12,13 However the exact amount needed for your body depends on many different factors and should be discussed with your doctor or a registered dietitian.
- What kinds of carbohydrates? – Some carbohydrate foods cause big increases in blood sugar (called high-glycemic index foods) while others do not (called low-glycemic foods). Low glycemic foods include soy products, beans, fruits, whole grain bread, oats, and lentils. High glycemic foods that are best to avoid include sweets, white bread, potatoes, and white rice.14
- Timing and Absorption Factors? – Fiber, protein, and fats slow the rate of carbohydrate absorption. Decreasing the rate of absorption is important in preventing large increases in blood sugar. Try building meals that pair carbohydrates with sources of fiber (whole grains, legumes, fruits and veggies), proteins, and fats. A good example is brown rice paired with grilled salmon and a tossed green salad topped with pumpkin seeds and an olive oil based dressing.
4. Cut down on added sugars – The American diet is full of unhealthy added sugars! Cutting these items out of your diet can help keep you and your baby healthy.
- Cut out sugary drinks like sodas and sweet teas. Try flavored sparkling
- Minimize pre-packaged sweets like cookies, candy, and cakes. Replace with fresh/frozen/dried fruits, honey-roasted peanuts, dark chocolate, or maybe a baked apple.
5. Monitor your weight gain – Gaining weight within recommendations and avoiding excess weight gain decreases the risk for diabetes.
- One way to control weight gain is by eating a nutrious and satisfying diet (described above).15
- Controlling portion sizes can be an important part in regulating your weight gain.
- This CDC site can help you estimate the average number of calories you need each day.
Recommendations for healthy weight gain during pregnancy:
Weight Category | Prepregnancy BMI (kg/m2) | Recommended total weight gain (lbs)* |
Underweight | <18.5 | 28 - 40 lbs |
Normal weight | 18.5 - 24.9 | 25 - 35 lbs |
Overweight | 25.0 - 29.9 | 15 - 25 lbs |
Obese | ≥30.0 | 11 - 20 lbs |
*Recommended weight gain is higher for people who are pregnant with more than one fetus.
Institute of Medicine (US) and National Research Council (US) Committee to Reexamine IOM Pregnancy Weight Guidelines. Weight Gain During Pregnancy: Reexamining the Guidelines. Rasmussen KM, Yaktine AL, editors. Washington (DC): National Academies Press (US); 2009. PMID: 20669500.
How can I safely exercise before and during pregnancy? –Staying active in pregnancy can help maintain metabolic health but it is important to always check with your doctor before beginning any exercise routine during pregnancy.16 One of the best ways to prevent elevated blood sugar is exercising early on in and throughout the duration of pregrnancy.17 Physical activity can help your muscles take up glucose, which is helpful in managing blood sugar.18
*It is important to consult your doctor before beginning a new exercise routine during pregnancy!*
1. Physical activity throughout pregnancy can help set the stage for good metabolic health.
- Engaging in moderate-intensity aerobic activity for at least 150 minutes weekly (for example, 30 minutes each day, 5 days a week) is highly beneficial during pregnancy.16
2. Some safer forms of physical activities in pregnancy are as follows17 :
- Walking— This activity is easy on your joints and doesn't require any equipment. Take a walk around your neighborhood or a local park if the weather is good. In bad weather, try walking laps inside your nearest indoor mall!
- Swimming & water workouts— Water sports are easy on your muscles and joints. Try your local community pool.
- Stationary bicycling— This is a great workout and is a safer option than a normal bike.
- Modified Yoga & Modified Pilates—Yoga reduces stress, improves flexibility, and teaches mindful breathing. Prenatal yoga and prenatal pilates classes are designed specifically for pregnancy and consider experiences specific to pregnancy such as a shifting sense of balance.
3. Use local and online resources for free and fun ways to stay active during your pregnancy. Your city's official website is a great place to start.
* In specific instances, it is better to avoid exercise in pregnancy. Check with your doctor to determine whether or how it may be safe for you to exercise in pregnancy. Exercise can be dangerous in certain health conditions including but not limited to the following: certain types of heart and lung diseases, cerclage, twin or triplet pregnancies with increased risk of preterm labor, placenta previa (after 26 weeks), preterm labor, preeclampsia, and severe anemia.16
Takeaways
Maintaining normal blood sugar during pregnancy is an important way to protect your health. Pregnancy hormones can decrease your body’s response to insulin, and make it more difficult to maintain normal blood sugar. Eating a nutritious and balanced diet as well as being physically active (if advised by your doctor) can help regulate blood sugar. These healthy habits can help you and your baby stay healthy during and after your pregnancy!
Kate Jurek, MS4
Christine D. Garner, PhD, RD, CLC
References:
1. Egan, A.M., Dow M.L., and Vella A., A Review of the Pathophysiology and Management of Diabetes in Pregnancy. Mayo Clinic Proceedings, 2020. 95(12): p. 2734-2746.
2. Dooley, S.L., Metzger B.E., and Cho N.H., Gestational Diabetes Mellitus: Influence of Race on Disease Prevalence and Perinatal Outcome in a U.S. Population. Diabetes, 1991. 40(Supplement_2): p. 25-29.
5. Weickert, M. O., and Pfeiffer A.H., Impact of Dietary Fiber Consumption on Insulin Resistance and the Prevention of Type 2 Diabetes. The Journal of Nutrition, 2018. 148(1): p. 7–12.
8. Domingo, J. L., Bocio, A., Falcó, G., and Llobet, J.M., Benefits and risks of fish consumption Part I. A quantitative analysis of the intake of omega-3 fatty acids and chemical contaminants. Toxicology, 2007. 230(2-3): p. 219–226.
11. Elsayed, N.A., Aleppo, G., Aroda, V.R., Bannuru, R.R., Brown, F.M., Bruemmer, D., Collins, B.S., Hilliard, M.E., Isaacs, D., Johnson, E.L., Kahan, S., Khunti, K., Leon, J., Lyons, S.K., Perry, M.L., Prahalad, P., Pratley, R.E., Jeffrie Seley, J., Stanton, R.C., Gabbay, R.A., 15. Management of Diabetes in Pregnancy:Standards of Care in Diabetes—2023. Diabetes Care, 2023. 46, S254–S266.
12. Snetselaar, L.G., Jesus, J.M., DeSilva, D.M., and Stoody, E.E., Dietary Guidelines for Americans, 2020-2025: Understanding the Scientific Process, Guidelines, and Key Recommendations. Nutrition Today, 2021. 56(6), p. 287–295.
13. Sweeting, A., Mijatovic, J., Brinkworth, G.D., Markovic, T.P., Ross, G.P., Brand-Miller, J., and Hernandez, T.L., The Carbohydrate Threshold in Pregnancy and Gestational Diabetes: How Low Can We Go?. Nutrients, 2021. 13(8), p. 2599.
15. Rasmussen, K.M., Yaktine, A.L., and Institute of Medicine (US) and National Research Council (US) Committee to Reexamine IOM Pregnancy Weight Guidelines (Eds.). Weight Gain During Pregnancy: Reexamining the Guidelines, 2009. National Academies Press (US).
17. Guo X, et al., Improving the effectiveness of lifestyle interventions for gestational diabetes prevention: a meta-analysis and meta-regression. An International Journal of Obstetrics and Gynecology, 2018. 126(3): p. 311-320.
