Gestational diabetes mellitus (GDM) is diabetes that happens when a woman is pregnant. Diabetes is a higher level of glucose in the blood than is normal. The levels often return to normal after delivery.
Large Baby Due to Gestational Diabetes
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Glucose in the blood comes from food and glucose stored in the liver. Insulin helps glucose move from the blood to the cells. Problems making or using insulin makes blood glucose levels rise. This leads to GDM. It is not clear what causes some to develop GDM. Changes in hormones during pregnancy may play a role.
Things that increase the risk of GDM include:
Symptoms are often not present with GDM. Some may have:
GDM testing is done as part of routine prenatal screening at 24 to 28 weeks of pregnancy. It may be done earlier for those at high risk.
A blood tests will check blood glucose levels. Other tests will be done if the first test shows high blood glucose. These tests are more sensitive and will help to confirm GDM and guide treatment.
Extra blood glucose during pregnancy acts as excess food for the baby. The baby then grows larger than normal. This can lead to increased risk of cesarean section or very high blood pressure called eclampsia. The baby also has a higher risk of injury during birth, like shoulder injury.
The goal of treatment is to keep blood glucose at normal levels. This will help reduce problems to both mother and baby. The care team will make a glucose management plan. It will include how to use exercise, meal plans, and medicine to manage blood glucose. Steps may include:
Blood glucose can be checked throughout the day. Home devices can test small amounts of blood for glucose levels.
A home urine test may also be needed if blood glucose rises too high. The test can show if blood glucose has risen too high. It can lead to a problem called ketoacidosis. This will need medical care because it can quickly harm the woman and the growing baby.
Glucose is affected by foods you eat in different ways. A meal plan can help to balance the effect a meal has on glucose. Most plans will focus on eating 3 meals and 2 to 3 snacks per day. A dietitian can help to make balanced meal plans.
Physical activity makes it easier for glucose to move from the blood into cells. It can improve immediate blood glucose levels and overall management. Exercise also has many benefits for pregnancy. General goals include movement on most days and at least 2.5 hours of exercise.
Medicine may be needed to better control glucose. It may be one of the following:
Steps that may decrease the risk of GDM include:
American College of Obstetricians and Gynecologists
American Diabetes Association
Canadian Diabetes Association
Women's Health Matters
American College of Obstetricians and Gynecologists Committee on Practice Bulletins—Obstetrics. Practice Bulletin No. 190: Gestational Diabetes Mellitus. Obstet Gynecol. 2018 Feb;131(2):e49-e64.
Gestational diabetes. American Diabetes Association website. Available at: https://www.diabetes.org/diabetes/gestational-diabetes. Accessed January 14, 2020.
Gestational diabetes mellitus (GDM). EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/gestational-diabetes-mellitus-gdm. Updated December 18, 2019. Accessed January 14, 2020.
Last reviewed September 2020 by
EBSCO Medical Review Board
Beverly Siegal, MD, FACOG
Last Updated: 08/25/2020