Welcome back, Mamas! Whether you’ve recently been diagnosed with gestational diabetes or you're just learning how to manage it, you might have come across the term HbA1c during your pregnancy journey.
But what does this test really tell you about your blood sugar control?
Is it as important during pregnancy as it is in other stages of life?
Understanding the role of HbA1c can be key to managing your health, both during and after pregnancy, and it’s a tool your healthcare provider may use in certain situations. So today, we’ll explain what HbA1c is, how it works, and how it relates to pregnancy and postpartum health, so you can feel confident in understanding your care.
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Hemoglobin A1c
HbA1c, also called glycated hemoglobin, is a blood test that measures your average blood sugar levels over the past approximately three months.
Hemoglobin is a protein in your red blood cells that carries oxygen to your body’s tissues. When glucose (sugar) is present in the bloodstream, it binds to the hemoglobin. The more glucose in the blood, the more hemoglobin becomes glycated, meaning it has sugar attached to it.
Red blood cells live for about 90 days, so HbA1c gives a snapshot of how well your blood sugar has been managed over that period.
The result is expressed as a percentage, reflecting the amount of hemoglobin that’s glycated. For example:
A normal HbA1c for non-pregnant individuals is below 5.7%.
An HbA1c between 5.7-6.4% indicates prediabetes.
An HbA1c of 6.5% or higher on two separate tests is diagnostic for diabetes.
While daily fingersticks or continuous glucose monitors (CGMs) show your current blood sugar levels, HbA1c is a useful longer-term indicator of blood sugar trends, giving you and your provider an idea of how well you’ve been managing your blood sugar over time.
How HbA1c Relates to Pregnancy
During early pregnancy, HbA1c can be a valuable tool! In the first trimester, your provider might check your HbA1c to understand how well your blood sugars were controlled before you got pregnant or to screen for undiagnosed type 2 diabetes.
This is especially important if you have risk factors for diabetes, such as being overweight, having a family history of diabetes, or having had gestational diabetes in a previous pregnancy.
Early in pregnancy, HbA1c levels remain relatively stable and can give insight into blood sugar levels before pregnancy because your blood volume and red blood cell turnover are still relatively normal. So, if your HbA1c is elevated in the first trimester, it could indicate that you had high blood sugars even before pregnancy.
However, as your pregnancy progresses, your body undergoes several changes, particularly an increase in blood volume and a faster turnover of red blood cells. This increase in blood volume means your red blood cells don’t live as long, which reduces the accuracy of HbA1c in reflecting your true blood sugar levels.
Even if your HbA1c shows a “normal” value after the first trimester, it doesn’t necessarily mean your blood sugars are well-controlled during pregnancy. For this reason, providers rely more on daily blood glucose readings to get a more accurate and timely understanding of your blood sugar control.
Use After the First Trimester
Despite its limitations after the first trimester, some healthcare providers may still choose to periodically check your HbA1c throughout pregnancy with diabetes. This isn’t necessarily a bad thing — providers may be looking for significant changes or very high levels, which can indicate poorly controlled diabetes.
But it’s important to remember that while HbA1c can offer a rough idea of how your blood sugar levels are trending, it’s not the gold standard during pregnancy. Your daily blood sugar readings (through fingersticks or CGMs) are much better indicators of how well you’re managing your blood sugar during pregnancy.
Postpartum Testing with HbA1c
After your baby is born, it’s crucial to follow up with your provider to check if your gestational diabetes has resolved or if you may be at risk for type 2 diabetes.
The gold standard for postpartum testing is the 2-hour glucose tolerance test (GTT), which involves drinking a glucose solution while fasting and measuring how your body processes sugar at intervals afterward.
While HbA1c may seem like a more convenient option, it’s not the best way to screen for diabetes in the immediate postpartum period.
After delivery, your body goes through significant changes — your hormones fluctuate, blood volume shifts, and red blood cell turnover is still affected. These changes make the HbA1c less accurate in reflecting true blood sugar levels during this time.
For example, if your HbA1c looks normal after giving birth, it doesn’t necessarily mean your blood sugars are under control. That’s why the 2-hour glucose tolerance test is the preferred method for screening in the months after delivery. It provides real-time insight into how your body processes glucose now that the pregnancy hormones are no longer influencing your insulin resistance.
Long-Term Use of HbA1c for Diabetes Screening
While HbA1c isn’t the best option for immediate postpartum screening, it does play an important role in your long-term health. Once your body has stabilized after pregnancy (usually after several months postpartum), HbA1c becomes a reliable tool again for evaluating your blood sugar control.
If you’ve had gestational diabetes, you’re at higher risk of developing type 2 diabetes later in life.
Your provider will likely check your HbA1c periodically, along with other blood sugar tests, to ensure your levels remain within a healthy range. For long-term diabetes screening, HbA1c is incredibly useful because it reflects your average blood sugars over time and helps catch any rising trends before they turn into full-blown diabetes.
It’s a good idea to establish routine check-ups with your primary care provider, especially if you’ve had gestational diabetes. Keeping an eye on your HbA1c over time can help you manage your risk and take proactive steps to prevent or delay the onset of type 2 diabetes.
Wrapping Up
Be sure to talk with your healthcare provider about your blood sugar management plan, and don’t hesitate to ask questions about the tests they’re using to monitor your health.
After all, staying informed and proactive is the best way to ensure both you and your baby stay healthy!
Until next week, Mamas!
Disclaimer: The information provided in this blog post is intended for general informational and educational purposes only. It is not intended to replace or substitute professional medical advice, diagnosis, or treatment. Always seek the advice of your healthcare provider with any questions you may have regarding a medical condition or your health. Never disregard professional medical advice or delay seeking it because of something you have read in this blog. GDMamas, LLC assumes no liability for inaccuracies, errors, or omissions in the information presented.
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