Women's Healthcare Topics

Gestational Diabetes a High Risk Pregnancy

Reviewed by James Brann, M.D.

What Causes Gestational Diabetes?

Gestational diabetes is one of the most common pregnancy complications, and it affects between 2 to 10 percent of all pregnancies. This condition is characterized by high blood sugar that starts ( or is first diagnosed) during pregnancy. Gestational diabetes typically goes away after your baby is born. However, over 50 percent of women who experience gestational diabetes will develop type 2 diabetes later in life.

To understand how gestational diabetes develops, you have to understand a few basic principles of how your endocrine system works. When you eat, most of your food breaks down into a type of sugar called glucose, which enters your bloodstream. Insulin (a hormone produced by the pancreas) opens your cells so they can use glucose as energy.

When you're pregnant, the hormones produced by the placenta inhibits the effects of insulin. As a result, your cells aren't able to respond to insulin as well as they did previously. To compensate for this resistance to insulin, a healthy woman's pancreas will respond by secreting more insulin. You may actually require three times the normal amount of insulin to support a healthy pregnancy.

Gestational diabetes occurs when your pancreas can't keep up with the increased insulin demand. When you don't have enough insulin, blood glucose can't leave your bloodstream and be changed into energy. As a result, glucose rises to high levels in your blood – which causes gestational diabetes.

Untreated Gestational Diabetes and Your Baby

Gestational diabetes usually doesn't begin until the middle half of pregnancy – often around 20 to 24 weeks pregnant. At this stage of pregnancy, your baby's body has already been formed. Because of this fact, gestational diabetes doesn't cause the type of birth defects that sometimes occur in babies whose mothers had pre-existing diabetes prior to pregnancy.

However, gestational diabetes that is not treated or is poorly controlled can still hurt your developing baby. The extra blood glucose that you have in your blood can cross the placenta and give your baby high blood glucose levels. As a result, your baby's pancreas produces extra insulin to get rid of the glucose, and because your child is getting more glucose than he or she requires, the extra glucose is stored as fat. This leads to a condition called "macrosomia" – an overly large baby.

Macrosomia is defined as a baby with a birth weight of 9 pounds and 15 ounces (4,500 grams) or more. Babies who are born too fat are harder to deliver vaginally. Mom will face a longer labor, and she may have to deliver with assisted vaginal delivery techniques – like vacuum extraction or use of forceps.

When mom delivers vaginally, a baby with macrosomia is at risk for shoulder dystocia during birth – his or her shoulder gets stuck behind your pubic bone. This is a rare but life-threatening situation that can cause severe injury or death of the baby. Babies with shoulder dystocia can sustain birth injuries during delivery, like broken clavicles, fractured collarbones, and nerve damage called brachial palsy – a condition characterized by loss of movement and weakness in the baby's arm that occurs when the nerves around the shoulder get damaged during childbirth.

Because of these risks associated with a vaginal birth, it is often recommended that women with overly large babies have a cesarean delivery.

In addition, babies of mothers with uncontrolled gestational diabetes can develop low glucose levels (a condition called hypoglycemia) in the first few hours after delivery. Hypoglycemia develops when the baby's source of glucose, which came from mom, is interrupted after the umbilical cord is clamped. Without the glucose from mom, the baby will end up with low blood sugar.

Babies born of diabetic mothers can have a number of other health problems, including breathing problems after birth (because their lungs tend to develop more slowly and may not be completely mature at birth) and jaundice. In addition, these babies are at elevated risk for obesity and type 2 diabetes in the future.

When diabetes is controlled during pregnancy, your baby's risk for health complications is lower.

Learn about diabetes starting in pregnancy or gestational diabetes.

Screening Guidelines for Gestational Diabetes

To minimize the risk of complications, all pregnant women will be screened for gestational diabetes during pregnancy. Screening is often performed between 24 and 28 weeks of pregnancy. You may be tested earlier for this pregnancy-induced diabetes if you are at higher risk for the condition.

Risk factors for gestational diabetes include:

  • There's a strong family history of diabetes

  • You were overweight before your pregnancy

  • Sugar (glucose) was found in your urine in a regular prenatal visit

  • You experienced gestational diabetes in a previous pregnancy.

If you have gestational diabetes, it's important that you get tested for diabetes in the years following delivery. Gestational diabetes is associated with an increased risk of type 2 diabetes.

In 2010, the International Association of Diabetes and Pregnancy Study Groups (IADPSG) – which is an international consensus group comprised of multiple diabetes organizations (including the American Diabetes Association) and obstetrical groups – recommended new gestational diabetes screening guidelines.

For women who are at higher risk for gestational diabetes (such as those who had pregnancy-induced diabetes in previous pregnancies), you may be screened for this pregnancy complication before 24 weeks pregnant.

To test for gestational diabetes, your blood may be drawn at random, or when you are asked to fast (abstain from eating for eight hours prior to the blood test).

If you are screened before 24 weeks pregnant, and your fasting blood glucose is less than 92 mg/dL or your random blood sugar (when your blood is drawn randomly at a prenatal visit) is less than 200 mg/dL, you will be asked to take a normal diabetes screening test. This 75-gram two hour glucose tolerance test is normally scheduled at 24 to 28 weeks of pregnancy.

On the other hand, if your fasting blood glucose is between 92 mg/DL and 126 mg/DL, you will be diagnosed gestational diabetes and no further screening tests will be required. Your pregnancy will be monitored closely with your doctor, and he or she will discuss your treatment options.

If your fasting blood glucose is above 126 mg/dL or your random blood glucose is higher than 200 mg/dL (which will be confirmed by a subsequent fasting blood test), you will be diagnosed with overt diabetes – you were diabetic before pregnancy, but you didn't realize it.

Between 24 and 28 weeks pregnant, all pregnant women with no known risk factors for gestational diabetes will be screened for the condition.

If your fasting blood glucose levels are higher than 126 mg/dL, or your non-fasting (which is taken randomly) blood glucose is higher than 200 mg/dL (which will be subsequently confirmed with a fasting blood test), you will be diagnosed with overt diabetes.

You will be asked to take a 75 gram two hour glucose tolerance test if your fasting blood glucose is less than 126 mg/dL or your random blood glucose is less than 200 mg/dL.

What Happens During a Glucose Tolerance Test?

When you take a glucose tolerance test, you will be asked to abstain from eating and drinking for 8 to 10 hours before the test. (You're allowed to drink sips of water, but nothing else.)

Once you arrive at your healthcare provider's office, blood will be drawn from your vein to measure your fasting blood glucose level. Next, you will be given a solution with 75 grams of glucose to drink. The solution is often described as tasting like a sugary orange soda.

Depending on the doctor, your blood may be taken again at one hour and then two hours after you drink the solution. In some cases, the technician will only take your blood test two hours afterwards.

Every healthcare organization uses a slightly different measurement for diagnosing gestational diabetes.

The American Diabetes Association diagnoses gestational diabetes if two of your blood glucose levels are higher than the following:

  • Fasting glucose level is higher than 95 mg/dL

  • One hour after you drink the solution, your blood glucose level is higher than 180 mg/dL

  • Two hours after, your glucose level is higher than 155 mg/dL

The World Health Organization considers you to have gestational diabetes if your fasting blood glucose levels are higher than 125 mg/dL or your two-hour blood glucose level is higher than 140 mg/dL.

According to the International Association of Diabetes and Pregnancy Study Groups (IADPSG), you have gestational diabetes if your fasting blood glucose levels are higher than 92 mg/dL, or your blood glucose level at 1 hour post-drink is higher than 180 mg/dL, or your two-hour blood glucose level is higher than 153 mg/dL.

Treatment for Gestational Diabetes

If you are diagnosed with gestational diabetes, your doctor or healthcare provider will talk to you about your treatment options. Once you're diagnosed, you will have more frequent prenatal visits. You may need to see your doctor every week or two. This is to monitor you and your baby's health.

Treating gestational diabetes is aimed at getting your blood glucose levels equal to that of the regular pregnant women. The goal is to reduce the risk of giving birth to an overly large baby.

Your doctor will probably recommend special meal plans and scheduled physical activity. You may also be asked to test your blood glucose levels on a regular, if not daily basis. Depending on your individual case, you may also need insulin injections. Only about 15 percent of women with gestational diabetes require insulin.

After your pregnancy, your blood glucose levels should return to normal levels. You can go back to eating your regular diet, and it is recommended that you breastfeed. ((Exclusive breastfeeding for at least six months is associated with an increased weight loss after pregnancy.)

The day after you deliver, you should check your blood sugar level to be sure that it's either normal or close to normal. Women with gestational diabetes have a 20 percent increased risk of developing type 2 diabetes within five to ten years after pregnancy.

The risk of developing type 2 diabetes is greatly influenced by your body weight. Obese women have a 50 to 75 percent risk of developing type 2 diabetes. Women of healthy weight only have less than a 25 percent risk. For this reason, women with a history of gestational diabetes can reduce their risk of type 2 diabetes by losing their pregnancy weight and exercising regularly.


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