Gestational diabetes: risks, testing and care in pregnancy

Being told you have gestational diabetes can feel worrying, but it is common enough that pregnancy care includes a routine check for it. With support from your care team, it can be managed. This article explains the basics in plain language.

What is gestational diabetes?

The NHS describes gestational diabetes as raised blood sugar that starts during pregnancy and usually goes away after the baby is born. It happens when the body cannot make enough insulin to meet the extra demands of pregnancy. It can occur at any stage but is more common in the second and third trimesters. The NIDDK links it with pregnancy hormones that reduce the body's ability to use insulin, and says genes and extra body weight may also play a role.

Symptoms

The NIDDK says gestational diabetes often has no symptoms. When symptoms do occur they are usually mild, such as increased thirst or needing to pass urine more often. The NHS adds dry mouth, tiredness, blurred vision and genital itching or thrush, and notes that several of these are common in pregnancy anyway. Because of this, testing matters even when you feel well.

Who is more likely to get it?

The NHS lists these risk factors:

• Being over 40
• A body mass index above 30
• A previous baby weighing 4.5 kg (10 lb) or more
• Gestational diabetes in an earlier pregnancy
• A parent or sibling with diabetes
• South Asian, Black, African-Caribbean or Middle Eastern family origin
• Previous weight-loss surgery such as gastric bypass

MedlinePlus lists similar factors, including overweight or obesity, a family history of diabetes, polycystic ovary syndrome and a previous baby weighing 9 pounds or more.

How is it tested?

According to the NIDDK, doctors test between 24 and 28 weeks of pregnancy. A glucose challenge test may be done first, and if it shows high blood glucose, an oral glucose tolerance test confirms the diagnosis. The NHS describes the oral glucose tolerance test as taking about 2 hours: you fast beforehand, have a blood sample, drink a glucose solution and have another sample after resting. If you have had gestational diabetes before, the NHS says you will usually be tested earlier. MedlinePlus says people at higher risk may be tested at their first prenatal visit.

How is it managed?

Your care team decides the plan. The NIDDK says management starts with a healthy eating plan and physical activity, and that insulin may be needed if these do not keep blood glucose in the target range. The NHS adds that you may be given a home testing kit to monitor your levels, that gentle activity such as walking or swimming often helps, and that tablets or insulin may be needed for some women. You should check with your midwife or doctor before starting a new activity. Birth is generally recommended before 41 weeks, the NHS says, and earlier delivery may be advised if there are health concerns or poor blood sugar control.

Possible effects on mother and baby

The NHS says well-controlled blood sugar lowers the risk of complications. Possible problems for the baby include excessive growth, which can make delivery more complicated, premature birth, low blood sugar after birth and jaundice. For the mother, the NHS notes a higher risk of pre-eclampsia, which is high blood pressure in pregnancy.

After the birth

Blood sugar usually returns to normal. The NHS says you should have a diabetes blood test 6 to 13 weeks after giving birth, then yearly if the result is normal. The NIDDK says women who had gestational diabetes are more likely to develop type 2 diabetes later, and their children are more likely to develop obesity or type 2 diabetes. A healthy weight, good food choices and staying active can lower these risks, according to the NIDDK. The NIDDK's prevention page also lists breastfeeding as a helpful step.

When to see a doctor

Contact your doctor or midwife if you notice signs of high blood sugar such as strong thirst, passing urine often or dry mouth, instead of waiting for your next scheduled test. Speak to your midwife or doctor about any pregnancy symptom that worries you.

In an emergency, call your local emergency number (112 in India, 911 in the United States).

This article is for education only and does not replace advice from your own doctor or midwife.