Maternal hyperglycemia is a condition of elevated blood sugar levels in a pregnant individual. It can arise in those with pre-existing diabetes or develop during pregnancy, known as gestational diabetes mellitus (GDM). This condition affects how the body uses sugar for energy and can influence the health of both the mother and the developing baby. While high blood sugar introduces challenges, it is a manageable condition with appropriate medical guidance and self-care.
Underlying Causes and Risk Factors
Maternal hyperglycemia occurs when the body cannot produce enough insulin to meet the increased demands of pregnancy. In the case of GDM, the underlying cause is insulin resistance, a state where the body’s cells do not respond effectively to insulin. This resistance is a normal physiological change during the second and third trimesters, driven by hormones produced by the placenta.
The placenta releases several hormones, including estrogen, cortisol, and human placental lactogen, that support the baby’s growth. These hormones, however, can also interfere with the mother’s insulin, making it less effective at regulating blood sugar. As the placenta grows, it produces more of these hormones, increasing insulin resistance. While most pregnant individuals can compensate by producing more insulin, some cannot, leading to the onset of GDM.
Several factors can increase a person’s likelihood of developing GDM, including:
- A pre-pregnancy body mass index (BMI) in the overweight or obese range.
- Maternal age over 25, with risk increasing further after 40.
- A family history of diabetes or a personal history of GDM.
- Conditions linked to insulin resistance, such as polycystic ovary syndrome (PCOS).
Health Implications for Mother and Baby
For the mother, uncontrolled hyperglycemia increases the risk of developing preeclampsia, a serious condition characterized by high blood pressure. It also raises the likelihood of needing a cesarean section (C-section) for delivery. Furthermore, individuals who have GDM are at a heightened risk of developing type 2 diabetes in the years following the pregnancy.
Excess glucose in the mother’s blood crosses the placenta, stimulating the baby’s pancreas to produce extra insulin. This insulin acts as a growth hormone, which can lead to excessive growth and fat deposition, a condition called macrosomia. A baby with macrosomia faces a greater risk of complications during birth, including shoulder dystocia, where the shoulder gets stuck during delivery.
After birth, the newborn may experience a rapid drop in blood sugar, a condition called neonatal hypoglycemia. This occurs because the baby’s pancreas is still producing high levels of insulin, but the glucose supply from the placenta has been cut off. Severe hypoglycemia can be dangerous and may require immediate feeding or intravenous glucose to stabilize the baby’s blood sugar.
Other potential issues for the newborn include a higher risk of jaundice and respiratory distress syndrome, a condition that makes breathing difficult. Children who were exposed to high glucose levels in the womb also have a greater likelihood of developing obesity and type 2 diabetes later in life.
Screening and Management
Screening for GDM is a standard part of prenatal care, typically occurring between 24 and 28 weeks of gestation. The process often begins with a glucose challenge test, which does not require fasting. For this test, the pregnant individual drinks a sugary solution, and an hour later, a blood sample is taken to measure blood glucose levels. If the results from this initial screening are elevated, a more definitive test is required.
The follow-up diagnostic test is the oral glucose tolerance test (OGTT), which requires fasting overnight. An initial blood sample is drawn to measure the fasting glucose level, after which the person drinks a more concentrated glucose solution. Blood is then drawn periodically over the next few hours to track how the body processes the sugar and formally diagnose GDM.
Once diagnosed, management focuses on maintaining blood glucose levels within a target range. The first line of approach involves lifestyle modifications, primarily centered on diet and physical activity. Dietary changes include eating balanced meals, monitoring carbohydrate intake, and choosing nutrient-dense foods. Regular, moderate exercise, as approved by a healthcare provider, can also help improve insulin sensitivity.
Consistent self-monitoring of blood glucose is a required part of management. This involves using a small device to prick the finger and test a drop of blood several times a day, such as before meals and one or two hours after. If diet and exercise are not sufficient to control blood sugar levels, medication may be prescribed. Metformin or insulin injections are common treatments used to manage hyperglycemia during pregnancy.