Pregnancy and Diabetes: When and Why Your Blood Sugar Levels Matter Most

When & Why Your Blood Sugar Levels Matters Most


The following is an excerpt from the book Pregnancy with Type 1 Diabetes by Ginger Vieira and Jennifer Smith, CDE & RD

There are two things you can definitely expect will be said to you by total strangers, friends, and several family members because you have diabetes:

“Doesn’t that mean your baby will be huge?” “So, is your baby probably going to get diabetes, too?”

Both questions are rather rude–sure–but both implications are also very far from accurate.

Yes: persistent high blood sugars during pregnancy can lead to a larger baby…but people without diabetes have very large babies, too. And people with diabetes have good ol’ fashioned regularly sized babies, too. There is no way to assure the size of a baby at birth. Skinny women can have huge babies just like an overweight woman can give birth to a very small baby. Women who eat a lot during pregnancy can have small babies! Very little of this is in our control. In the end, you can manage your diabetes extremely tightly and still have a larger than average baby because blood sugar control is not the only thing that impacts the size of your baby at birth, and more importantly, a larger baby is not the only or even most important complication a baby can experience due to mom’s elevated blood sugar levels. No: just because you have diabetes definitely does not mean your baby will have diabetes! And guess what, there’s nothing you can do during pregnancy to prevent or reduce your baby’s risk of developing diabetes…at least not that science and research is aware of at this time. So take a very deep breath, mama, because that is not something you can control, and your baby’s risk of developing type 1 diabetes is actually only about 2 percent higher than the risk of a non-diabetic woman’s baby developing type 1 diabetes. Feel free to share that little factoid with the many people who are going to ask you that question.

The simple truth is that our blood sugars will impact our baby’s growth, development, and well-being (and your own well-being) in different ways at different times:

Pre-Conception & 1st Trimester: Your blood sugars prior to getting pregnant and during the first trimester actually matter more than your blood sugars during any other part of your pregnancy!

In a nutshell: mom’s blood sugars and A1C levels prior to pregnancy–particularly the 6 months prior to pregnancy–will increase the risk of baby developing a birth defect.

If a birth defect (in any baby with a diabetic mom or not) is going to occur, it will happen during the first 8 to 10 weeks of the embryo’s life when the “body systems” are forming. Those “body systems” include: digestive systems, endocrine system, respiratory system, reproductive system, circulatory system, skeletal system, lymphatic system, muscular system, urinary system, nervous system.

Once those systems are developed, the fetus is growing and essentially “learning” for 9 months in utero how to use all the system that have been established. Some systems include organs that mature over time, such as the lungs, but once they are formed in those first 8 to 10 weeks, the birth defects already exist.

Again, this means that blood sugar management during the months prior to conception and during that first trimester is vitally important for helping to prevent the development of birth defects.

2nd Trimester: You know that cute little baby bump you’ll find yourself impatiently waiting to appear around month 4 or 5 or 6? Well, obviously, that’s your adorable little baby growing inside you! And what helps a baby grow faster? Sugar. As in…too much sugar in mama’s bloodstream.

The higher your blood sugar levels are, the more insulin your baby’s pancreas is going to produce in order to manage its own blood sugar levels. (It’s painfully amusing to think about the fact that there will be a fully functioning pancreas, plenty of real insulin and a totally healthy immune system in your body that you have no access to!)

What does the baby do with all that extra sugar? Since insulin is an energy-storing hormone, excess levels of insulin from mom’s persistently elevated blood sugar levels means your baby is going to be storing more body fat. Now, having a high blood sugar here or there, or for a few hours each day doesn’t mean your baby is going to be huge, but high blood sugars and high A1C levels persistently throughout your pregnancy, particularly in the 2nd and 3rd trimester will likely result in a larger baby and can mean you’ll likely need a cesarean section to safely birth your child.

3rd trimester: There are two additional complications that can arise from persistent high blood sugars during the third trimester.

a) Pre-eclampsia: The first is your risk of developing pre-eclampsia. Pre-eclampsia is marked by high blood pressure, swelling in the face, and protein in the urine. (Swelling can occur in the hands and feet as well, but most pregnant women will experience swelling in hands and feet. The real tell-tale swelling of pre-eclampsia is when it occurs in the face.) The more severe the state of the pre-eclampsia is, the more it can include dysfunction in the kidneys and your liver, disturbed vision, low blood platelet levels, low red blood cell levels, and fluid in the lungs that can cause shortness of breath.

Pre-eclampsia becomes eclampsia if or when or a woman experiences a seizure–which can be life-threatening to both mom and baby. Women showing signs of pre-eclampsia will be closely monitored and sometimes hospitalized during the latter part of the pregnancy to prevent eclampsia.

Women with type 1 diabetes are at a higher risk of developing pre-eclampsia because of the added stress on our body systems due to elevated blood glucose levels. A study published in the medical journal, Diabetes Care, in November 2014 concluded that women with an A1C level higher than 6.0 percent during the 2nd and 3rd trimesters had a significantly higher risk of developing pre-eclampsia.

As a woman with type 1 diabetes, your OBGYN team should and will ask you at every appointment during your pregnancy if you’ve noticed swelling in your face, hands and feet. Your blood pressure should and will be measured at every appointment. And kidney function and protein output in your urine should and will be measured prior to your pregnancy and at the start of your pregnancy in order to have something to compare to during the 3rd trimester when you’re being closely watched for pre-eclampsia. Most women with type 1 diabetes will experience some protein output in their urine simply because our kidneys do have to work harder than non-diabetics, but your doctor will be looking for a drastic elevation in that output.

b) Baby’s Blood Sugar at Birth: The second reason your blood sugar levels matter during the 3rd trimester is because your baby’s body will become accustomed to producing a certain amount of insulin to meet the amount of glucose in your bloodstream.

A healthy and “normal” blood sugar level for a newborn baby is anything above 45 mg/dL.

When baby is born–in a mother whose blood sugar levels were persistently high during the last trimester–it is quickly disconnected from that bloodstream but still producing the same amount of insulin during the first few hours of life outside of mom’s body. This means that baby’s blood sugar levels will be low, possibly dangerously low, and they will need a bottle immediately after birth to prevent having seizures from hypoglycemia.

You may have been told or read that all babies born to mother with diabetes will be “whisked away” to have their blood sugar checked and given a bottle, but the reality is that all babies are “whisked away” eventually after being born for a mere few moments to be cleaned up. If you give birth vaginally, the baby will be immediately placed on your chest but yes, eventually taken to a table in the same room to be cleaned up and assessed. If you give birth via c-section then the baby will first be cleaned up and assessed and then brought to you…but this really is within 10 minutes or less unless there are immediate concerns.

Unless baby is showing obvious physical signs of hypoglycemia immediately after birth, your baby’s blood sugar is not actually tested until approximately 1 hour later. Then 1 hour after that, and 1 hour after that. Each test is looking for a blood sugar above 45 mg/dL, otherwise a bottle with sugar water or formula will be administered.

Generally, a baby whose blood sugar levels were mildly low at birth will stabilize within a few hours of being born. This is common for women with type 1 diabetes, it can clearly be treated, but you can help prevent it entirely with tight diabetes management particularly during your 3rd trimester.

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Ginger Vieira

Ginger Vieira has lived with Type 1 diabetes and Celiac disease since 1999, and fibromyalgia since 2014. She is the author of Dealing with Diabetes Burnout & Emotional Eating with Diabetes & Your Diabetes Science Experiment. Ginger is the Editorial Director at DiabetesDaily, with a B.S. in Professional Writing and certifications in cognitive coaching, video blogging, record-setting competitive powerlifting, personal training, Ashtanga yoga, and motivational speakingCOMING in January 2017: Ginger's 4th book written with co-author Jennifer Smith, CDE & RD, "Pregnancy with Type 1 Diabetes: Your Month-to-Month Guide to Blood Sugar Management." 

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Ginger Vieira
Ginger Vieira

Author of “Your Diabetes Science Experiment” and “Emotional Eating with Diabetes,” Ginger Vieira has lived with Type 1 diabetes and Celiac disease since 1999. Today, she is a certified cognitive coach and diabetes coach at Living in Progress, creates diabetes video blogs for her YouTube Channel, and creates regular freelance content for Diabetes Daily and other publications. In 2009 and 2010, Ginger set 15 records in drug-tested powerlifting with a 308 lb deadlift, 190 lb. bench press, and a 265 lb. squat. She lives in Vermont with two dogs and her fella.

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