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Pregnancy & Prenatal Testing

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First Trimester: Blood Glucose or Hemoglobin A1c Testing

Sometimes a healthcare practitioner will screen for pre-existing diabetes in a pregnant woman at the first prenatal visit or during the first trimester, especially if the woman has risk factors for diabetes, such as family history. This is different than diabetes that develops during pregnancy (gestational diabetes), which is routinely screened for in the second trimester.

A fasting blood glucose, a 2-hour glucose tolerance test, or a hemoglobin A1c may be used for identifying pre-existing diabetes in pregnant women. (See the article on Glucose Tests for more details.) An elevated level of blood glucose may mean that the woman has diabetes. She will receive additional testing to confirm the diagnosis and, if diagnosed, will receive treatment to manage the condition.

A different set of tests is used to diagnose gestational diabetes. Read the section Second Trimester: Blood Glucose for more on this.

Centers for Disease Control and Prevention: Type 1 or Type 2 Diabetes and Pregnancy