August 28, 2023
There’s a lot of testing that takes place during pregnancy. The oral glucose challenge test, or glucose screening test, may be one of the easiest tests you’ll take during the 10 months of pregnancy. You drink a sugary drink and get your blood drawn an hour later. While the test seems simple enough, the results can make your pregnancy a lot more complicated.
The glucose test — or glucose monitoring if you and your doctor choose that route — helps determine whether you’ve developed gestational diabetes, a type of diabetes specific to pregnancy. “If you have gestational diabetes, it’s critical to get it under control,” says Lauren Vollrath, an MU Health Care family nurse practitioner. “Left uncontrolled, it can be dangerous for you and the baby.”
To help you understand gestational diabetes — and the importance of the glucose challenge test — Vollrath shares six facts:
1. Some People Are at Higher Risk for Gestational Diabetes
Gestational diabetes impacts up to 10% of pregnancies yearly in the United States. But not everyone has the same risk of developing it.
Certain factors put you at higher risk, including:
- Age: Your risk for gestational diabetes goes up with age, beginning at 25.
- Body mass index (BMI): If your BMI — the ratio of your weight to your height — is 30 or more, your risk of developing gestational diabetes is higher.
- Prior pregnancies: Having gestational diabetes in a previous pregnancy slightly increases your risk of developing it again. Prior unexplained pregnancy loss, giving birth to a large baby (more than 8.5 pounds) or being born as a large baby also increases your risk — it’s possible you or your mother had undiagnosed gestational diabetes in previous pregnancies.
- Culture: People of Hispanic or Native American descent have a 40% to 60% higher risk of developing gestational diabetes than non-Hispanic white people.
- Current health: Your risk increases if you have polycystic ovary syndrome (PCOS), high blood pressure (hypertension), low sugar in your urine or take glucocorticoids (anti-inflammatory medication).
- Family history: If a first-degree relative had gestational diabetes or you have a strong family history of diabetes, you have a higher risk.
“A good diet, regular exercise and maintaining a healthy weight can help decrease your risk, but some people are just predisposed to gestational diabetes,” says Vollrath. “At the same time, there are completely healthy athletes who somehow develop it. The only reasonable explanation is an unknown family history or something wrong with the placenta — because the placenta is what causes gestational diabetes.”
2. The Placenta Is the Problem
You can blame your placenta — the temporary organ in the uterus — for your body's blood sugar issues. During pregnancy, the placenta releases a hormone that causes your body to use insulin less efficiently. Insulin’s job is to regulate the amount of sugar (glucose) in your blood.
The placenta doesn't release hormones until it’s fully grown (usually during the second trimester). All women experience some changes to their insulin later in pregnancy. But if you have insulin resistance before pregnancy, the hormones may push the limits of what your body can effectively manage.
“The good news is that once the baby is born and the placenta is out, your hormones (and your insulin levels) should return to normal,” Vollrath says. “But we recommend doing a two-hour glucose test at your six-week postpartum appointment to ensure you won’t continue having insulin issues.”
3. Having Gestational Diabetes Once Doesn't Mean You'll Have It Again
Gestational diabetes can develop during any pregnancy. Just because you didn't have it with your first or second pregnancy doesn't mean you won’t develop it with subsequent pregnancies.
On the flip side, just because you had gestational diabetes during a pregnancy does not mean you'll automatically have it again. It does raise your risk, though.
“People who previously had gestational diabetes have a 25% chance of recurrence with each pregnancy,” Vollrath says. That’s compared to the less than 1% chance of developing gestational diabetes if you didn’t have it in a prior pregnancy. “Doctors screen people with prior gestational diabetes much sooner and closely monitor it throughout the pregnancy.”
4. Gestational Diabetes Can Change Your Pregnancy and Impact Your Baby’s Birth
Experts recommend screening for gestational diabetes between 24 and 28 weeks. But if your doctor establishes that you are at higher risk for gestational diabetes, they may also want to test you earlier in the pregnancy — possibly at your first prenatal visit. That way, you can take the necessary steps to manage your blood sugar and protect your baby's development.
Someone who has gestational diabetes may undergo:
- Dietary changes to help balance blood sugar levels
- Increased physical activity, which can reduce blood sugar levels
- Glucose testing weekly or daily to monitor your blood sugar
- Growth scans every four weeks to monitor the baby’s size
- Antenatal testing (starting at 32 weeks) to check the baby’s breathing and fluid level
- Insulin injections if diet and exercise modifications aren’t working to control the condition
If your gestational diabetes remains uncontrolled, your pregnancy may at considered "high risk" for:
- Operative delivery that may include a caesarian section or the use of forceps or vacuum to help deliver a larger baby
- Preterm labor or delivery
- Preeclampsia (high blood pressure in pregnancy)
- Shoulder dystocia and birth trauma if the baby gets stuck during delivery
“There’s a 12% higher risk for preeclampsia if you have gestational diabetes,” Vollrath says. Preeclampsia impacts the blood going to the placenta, can affect fetal growth and may cause preterm birth. “So that’s something we monitor very closely.”
5. Uncontrolled Gestational Diabetes Can Affect Your Baby's Development
Uncontrolled gestational diabetes can affect your child's birth and development. "In poorly controlled diabetes, you see more issues,” Vollrath says. “Some babies just can’t develop appropriately when diabetes is left untreated.”
The impact can occur both before and after birth, possibly causing:
- Birth trauma if the baby is large
- Higher risk of obesity and diabetes during childhood
- Impaired fine and gross motor function
- Higher rates of inattention or hyperactivity issues
- Hypoglycemia (low blood sugar) and respiratory distress following birth
6. Gestational Diabetes Increases Your Lifetime Risk of Developing Type 2 Diabetes
While insulin levels typically return to normal after pregnancy, gestational diabetes does leave you with an increased risk for Type 2 diabetes.
About 3.7% of people with prior gestational diabetes are diagnosed with Type 2 diabetes within nine months after delivery. About 50% of people with gestational diabetes develop Type 2 diabetes in their lifetime.
“Remember, gestational diabetes is just one risk factor for Type 2 diabetes,” Vollrath says. “Whether you have diabetes during pregnancy or not, you can lower your lifetime risk by modifying your diet, increasing your exercise and managing your weight.”
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