Gestational diabetes is one of the most common health issues that can occur during pregnancy. It happens when the mother is diagnosed with diabetes for the first time partway through the pregnancy. The key to minimizing the effects of gestational diabetes is diagnosing it early through the use of an oral glucose tolerance test. If gestational diabetes is not diagnosed correctly, it can lead to macrosomia in the baby (abnormally large fetal size), which puts the baby at risk for neonatal hypoglycemia, trauma, and other complications. It can also lead to jaundice, premature birth, birth asphyxia, and reduced uteroplacental perfusion (RUPP), which harms the child by reducing oxygen flow to the brain.
What is gestational diabetes?
During pregnancy, the body produces a larger amount of certain hormones that impact the placenta, and help to maintain a healthy pregnancy. This increase in hormones leads to insulin resistance, which increases the amount of glucose in the blood stream. This is normal in pregnancy, as this extra glucose is needed to support the baby. However, when insulin resistance becomes too great, and the amount of glucose in the bloodstream is very high, gestational diabetes can result (10).
Causes of gestational diabetes
During pregnancy, certain hormones are released that can lead to a mass amount of glucose in the blood. In addition, pregnancy hormones like placental lactogen can interfere with susceptible insulin receptors, which further increases blood glucose levels. When the amount of insulin produced is less than the amount needed to handle blood glucose levels, gestational diabetes can arise (1).
Risk factors for gestational diabetes
Risk for gestational diabetes increases if the patient has any of the following conditions (1):
- Age greater than 25 years
- A family history of type 2 diabetes
- Prior birth of a baby that weighed more than 9 pounds or had a birth defect
- Previous poor obstetric history
- High blood pressure and preeclampsia
- Too much amniotic fluid (polyhydramnios)
- An unexplained miscarriage or stillbirth
- Overweight before pregnancy
- Polycystic ovary syndrome
- A previous diagnosis of gestational diabetes or prediabetes, impaired glucose tolerance, or impaired fasting glycemia
Signs and symptoms of gestational diabetes
Gestational diabetes can be diagnosed through prenatal testing and screening. Signs and symptoms for gestational diabetes may include (9):
- Blurred vision
- Frequent infections, including those of the bladder, vagina, and skin
- Increased thirst
- Increased urination
- Nausea and vomiting
- Weight loss despite increased appetite
Diagnosing gestational diabetes through blood tests
The American Congress of Obstetrics and Gynecologists (ACOG) recommends that all pregnant women receive an oral glucose tolerance test between the 24th and 28th week of pregnancy to screen for gestational diabetes. Women who have risk factors for it may have this test earlier in the pregnancy, typically around the 18th week of pregnancy (1).
Usually, to test for gestational diabetes the pregnant woman will drink a syrupy solution, and her blood will be tested to check glucose level an hour later. A follow-up test is then given, whereby the patient fasts overnight and then has her blood sugar tested the next morning. After the test, she will drink a solution that has an even higher level of glucose than the syrupy solution given during the initial test. The patient’s blood glucose level will then be checked every hour for a period of three hours. If at least two of the blood glucose readings are higher than normal, the patient will be diagnosed with gestational diabetes (1).
Treatment and management for gestational diabetes
Once a patient is diagnosed with gestational diabetes, the physician will have her monitor her diabetes by testing her glucose level at home. The most common way involves obtaining a drop of blood from a finger and putting it on a device that will give a glucose reading. The goals of treatment are to keep blood glucose levels within normal limits during the pregnancy and to make sure the growing baby is healthy.
With gestational diabetes, frequent check-ups by the physician are essential, especially during the last three months of pregnancy. The physician will carefully monitor the patient’s blood glucose levels.
The medical team will also perform other tests to monitor the baby’s health. Tests used to monitor and protect the baby include:
- Fetal monitoring to check the size and health of the fetus.
- A nonstress test (NST), which measures the baby’s heart rate. The heart rate should increase when the baby moves. If the baby’s heart doesn’t beat faster during movement, the baby may not be getting enough oxygen.
- Amniotic fluid index (AFI), a measurement, calculated by measuring the depth of the amniotic fluid in four sections of the womb and adding them together.
- A biophysical profile (BPP), which combines a nonstress test with an ultrasound study of the baby. There is a scoring system that enables the physician to evaluate the baby’s heartbeat, movements, breathing, and overall muscle tone, and determine whether the baby is surrounded by a normal amount of amniotic fluid. The baby’s scores on heartbeat, breathing, and movement help the physician determine if the baby is getting enough oxygen. When the amniotic fluid index (AFI) is low, it may mean that the baby hasn’t been urinating enough. This could indicate that over time, the placenta has not been working as well as it should.
- Doppler flow studies test how well blood is flowing to the baby’s brain, organs and other parts of the body.
In addition to close monitoring, it is recommended that mothers with gestational diabetes be treated with dietary counseling, oral hypoglycemic medications, or insulin (5).
Gestational diabetes and birth injury
Currently, the American College of Obstetricians and Gynecologists (ACOG) and the American Diabetes Association recommend screening all pregnant women for gestational diabetes. Additionally, ACOG states that women who develop pregnancy-related diabetes should be re-tested 6 to 12 weeks after delivering their babies (1).
However, according to a 2010 study of one million patient records, only about two-thirds of pregnant women undergo screening tests for gestational diabetes. Among the 5% of women who tested positive for gestational diabetes, just 1 in 5 were screened again within six months of giving birth (2).
The findings are particularly concerning given that a recent large study, the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) trial, found that even subtle defects in maternal glucose metabolism during pregnancy led to health problems for mother and baby (2).
Gestational diabetes places mothers in the high-risk pregnancy category, as it poses an increased risk for complications during pregnancy, labor, and delivery. With proper monitoring and care, however, many of the risks associated with gestational diabetes can be mitigated, resulting in a healthy baby.
Mothers who have a high-risk pregnancy are referred to maternal-fetal specialists and require more frequent prenatal testing. In addition, these mothers are often advised to have a scheduled, early delivery in order to minimize the risks associated with their specific high-risk conditions.
In many cases, it is safest for babies of mothers with gestational diabetes to be delivered in a scheduled delivery prior to 40 weeks (3). If a mother’s diabetes is poorly controlled, delivery is recommended as early as week 36 (4). Although premature birth does have associated risks, in the case of diabetes, the benefits of early delivery outweigh the risks. With proper postnatal care, babies born at 36+ weekly typically do well.
Mothers with diabetes have high blood sugar levels, which are often passed on to the baby through the placenta (5). This large amount of energy is put towards growth, and can result in a baby being too large (macrosomic), which increases the baby’s risk of a traumatic birth. Babies with macrosomia are most safely delivered via C-section. If macrosomia goes undetected, this may result in a prolonged or arrested labor or in traumatic injury to the baby’s head or brain (6).
While in utero, babies are used to having a certain supply of glucose from the mother. Once they are born, they begin to produce their own energy stores. While in utero, babies produce larger quantities of insulin to process the existing larger supply of blood sugar. When babies of mothers with gestational diabetes are born, the amount of insulin they produce does not drop as quickly as their glucose supply does, since they are accustomed to a larger supply of glucose in utero (7). If they don’t take in enough energy as newborns, their blood sugars drop dangerously low. This is extremely problematic because blood sugar is the sole energy source for the brain. If low blood sugar (hypoglycemia) continues, brain cells begin to die, which can cause seizures and permanent brain damage. After birth, its very important to monitor the baby’s blood sugar, especially if their mother had diabetes, in order to prevent it from dipping too low (7).
Hypoxic-ischemic encephalopathy and cerebral palsy
Hypoxic-ischemic encephalopathy (HIE) is a brain injury caused by a lack of blood and oxygen flow to the brain. This can happen due to complications associated with diabetes, such as prolonged labor or traumatic delivery due to macrosomia (1, 3, 7). Medical practitioners are trained to recognize sentinel events and conditions that could potentially cause injury – and should be trained to avoid injury and provide care that is up to the ‘standard of care.’ If they do not provide proper care, the baby may suffer HIE and resultant cerebral palsy.
Neonatal seizures are one sign that a baby has neurological abnormalities. Seizures are abnormal electrical discharges in the brain and are very common in the presence of hypoxic-ischemic encephalopathy (HIE), as well as in neonatal hypoglycemia. Neonatal hypoglycemia can damage brain cells, which in turn can cause seizures. It is very important that medical professionals bring seizures under control because continuing seizures can make underlying brain damage worse.
Mothers with gestational diabetes can sometimes have poor placental perfusion, which can cause chronic intrauterine hypoxia and placental insufficiency. These conditions can cause the baby to produce too many red blood cells (7). Babies’ livers break down these red blood cells, releasing a substance called bilirubin into the blood. When too much bilirubin is released (hyperbilirubinemia), the baby’s skin and eyes can turn yellowish. This condition is called jaundice.
Jaundice is a sign that should be reported to a medical professional for immediate treatment. In some babies, jaundice goes away on its own, but in other cases, babies may need some help. When babies need help eliminating bilirubin, they are put under blue phototherapy lights. If jaundice isn’t treated properly, bilirubin can continue to accumulate to toxic levels and cross the blood-brain barrier. If bilirubin reaches the brain, it causes a form of brain damage called kernicterus – a condition which is always avoidable (8).
Gestational diabetes: Steps for a healthy pregnancy, labor, and delivery
Starting at 32 weeks of gestation, the mother should have prenatal testing done at least every two weeks. This includes a nonstress test with and ultrasound to assess the amniotic fluid index (AFI). An ultrasound to estimate fetal weight should be done at 36 to 39 weeks as well. If a mother with gestational diabetes has other complicating factors, such as obesity or preeclampsia, prenatal testing should be more frequent and a planned delivery may need to occur at an earlier date (3, 5).
Labor induction and gestational diabetes
It is common practice to induce labor prior to 40 weeks for women with gestational diabetes as a strategy to reduce complications, especially those related to macrosomia. Labor induction is often planned at 38 ½ to 39 weeks’ gestation and can occur when the baby’s lungs are mature, antepartum tests are normal, diabetes is under control, and the mother doesn’t have vascular disease (1).
ACOG recommends consideration of C-section delivery in diabetic women when estimated fetal weight exceeds 4500 grams. Some researchers recommend considering C-section delivery when the estimated weight is between 4000 and 4500 grams, after evaluating obstetrical history and clinical measurements of the pelvis. Physicians should be alerted to the possibility of cephalopelvic disproportion if dilation or descent stops during labor, and the baby’s estimated weight exceeds 4000 grams. These researchers also suggest consideration of C-section delivery in diabetic women who demonstrate significant protracted labor and failure of descent (1).
Physicians have to consider a number of factors when caring for a woman with gestational diabetes and her baby. Due to the variety and complexity of these issues, it is essential that medical professionals monitor and treat the mother and baby very closely throughout the pregnancy, labor, and delivery.
Legal help for gestational diabetes and birth injury
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All pregnant women must be screened for gestational diabetes around 28 weeks of pregnancy. If the initial glucose tolerance test indicates that an expectant mother might be diabetic, medical professionals should administer a more intensive three-hour glucose test. It is critical for a pregnant woman’s doctor to accurately read the results of gestational diabetes tests in order to prescribe the correct diet and medication.
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- Gestational Diabetes. (n.d.). Retrieved from http://www.questdiagnostics.com/home/physicians/health-trends/trends/gestational-diabetes.html.
- Caughey, A. B. (2018, July). Gestational diabetes mellitus: Obstetrical issues and management. Retrieved from https://www.uptodate.com/contents/gestational-diabetes-mellitus-obstetrical-issues-and-management.
- Kalra, B., Gupta, Y., & Kalra, S. (2016, June). Timing of Delivery in Gestational Diabetes Mellitus: Need for Person-Centered, Shared Decision-Making. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4900972/.
- Durnwald, C. (2018, October). Gestational diabetes mellitus: Glycemic control and maternal prognosis. Retrieved from https://www.uptodate.com/contents/gestational-diabetes-mellitus-glycemic-control-and-maternal-prognosis.
- Mandy, G. T. (2018, August). Large for gestational age newborn. Retrieved from https://www.uptodate.com/contents/large-for-gestational-age-newborn.
- Riskin, A., & Garcia-Prats, J. A. (2016, August). Infant of a diabetic mother. Retrieved from https://www.uptodate.com/contents/infant-of-a-diabetic-mother.
- Wong, R. J., & Bhutani, V. K. (2018, September). Treatment of unconjugated hyperbilirubinemia in term and late preterm infants. Retrieved from https://www.uptodate.com/contents/treatment-of-unconjugated-hyperbilirubinemia-in-term-and-late-preterm-infants.
- Gestational Diabetes: Testing and Treatment. (2018, October 17). Retrieved from http://americanpregnancy.org/pregnancy-complications/gestational-diabetes/.
- Gestational Diabetes. Retrieved from https://www.healthline.com/health/gestational-diabetes#causes.