What is normal blood sugar in pregnancy?

Blood sugar levels are evaluated with a glucose tolerance test. Pregnant women, who are at an increased risk of diabetes due to changes that take place during pregnancy, are given a glucose tolerance test at various times during pregnancy based on various additional risk factors. The test results may indicate the need for treatment for gestational diabetes or additional testing, or may indicate normal blood sugar levels.

Gestational Diabetes Testing

A pregnant woman is given a test for gestational diabetes between week 24 and week 28 of pregnancy, unless she is at high risk for failing the test. Women may be at increased risk due to personal or family history or genetic makeup.

Pregnant mothers who have an immediate family member with diabetes, are of African, American Indian, Asian, Hispanic or Pacific Islander descent, are over the age of 25 years, are overweight, have had gestational diabetes in a previous pregnancy, have given birth to a baby over nine pounds or have been diagnosed as pre-diabetic are more at risk for gestational diabetes. Women at high risk for gestational diabetes are often tested at the first prenatal visit.

How Does the Glucose Tolerance Test Work?

The glucose tolerance test is a measurement of how well the body tolerates the ingestion of glucose. The pregnant woman is told to fast for at eight hours prior to the test, and drink nothing but water on the morning of the test. When she arrives at the test site, her blood is drawn to measure her fasting blood sugar level.

Once the first blood draw has been completed, the pregnant mother is given a 100 gram bottle of glucose solution to drink in a limited amount of time. Once she drinks the solution, she remains in the office, and has another blood draw at hourly intervals for the next three hours.

What do the Gestational Diabetes Test Results Mean?

Many doctors will simply tell a patient that the test results were "normal" or "borderline," or that the test showed that the patient has gestational diabetes. Other doctors will reveal the actual results of the test, so that the patient can keep records of her blood glucose levels during pregnancy. According to the National Diabetes Information Clearinghouse, two abnormal readings indicate the presence of gestational diabetes:

• a fasting blood sugar reading of 95 or higher
• blood sugar of 180 or higher, one hour after drinking the glucose solution
• blood sugar of 155 or higher, two hours after drinking the glucose solution
• blood sugar of 140 or higher, three hours after drinking the glucose solution

A recent study published in Diabetes Care Magazine, however, indicates that danger-levels of blood sugar during pregnancy may be lower. According to this study, the following blood sugar readings are risky to a mother and baby:

• a fasting blood sugar reading of 92 or higher
• blood sugar of 180 or higher, one hour after drinking the glucose solution
• blood sugar of 153 or higher, two hours after drinking the glucose solution

Abnormal Blood Sugar During Pregnancy

Eating a healthy diet, staying active and following a doctor's instructions are important, after getting borderline or positive test results for gestational diabetes. Pregnant women diagnosed with abnormal blood sugar will be closely watched by their obstetrician to prevent harm to the baby, and will be given help with meal plans, exercise and even medication if necessary.