What is Gestational Diabetes and How Does it Affect Your Pregnancy?

Gestational diabetes mellitus (GDM) is a type of diabetes that develops because of the increased demands of pregnancy on the body. If not monitored closely, it can be dangerous for both mother and baby. These risks can be reduced if the condition is managed properly.

How does gestational diabetes occur?

Diabetes affects the way that body cells control glucose (sugar levels) and can cause levels to be both high (hyperglycemia) or low (hypoglycemia). Insulin is a hormone produced by the pancreas that helps to keep blood sugar levels under control by helping glucose to enter cells for energy use or storage.

During pregnancy, placental hormones (estrogen, progesterone, cortisol and human placental lactogen) increase and affect how insulin is used by the body – sometimes leading to insulin resistance. If the pancreas cannot respond to the increased demand for insulin then gestational diabetes develops.

As it is a progressive condition, it is usually screened for in the second trimester (at around 24–28 weeks). GDM usually dissipates following the birth of the baby and placenta, and as the body readjusts back to normal.

How does gestational diabetes affect mothers?

Although pregnancy complications only occur in about 7% of cases, mothers may worry about gestational diabetes as it classes them as high risk, and the consequences of poorly controlled GDM can be serious.

Hyperglycemia from GDM can lead to high blood pressure and pre-eclampsia (a combination of blood pressure and other body system disorders), which are dangerous for both mother and baby.

As well as causing problems with pregnancy, it can also affect labour and delivery. GDM limits the choice of delivery methods and increases the risk of birth trauma, maternal injury, operative or instrumental delivery. The negative implications for the baby, short and long term, will also cause mothers anxiety. Long term, GDM places mothers at higher risk for developing type 2 diabetes later in life.

How does gestational diabetes affect the baby?

When high levels of glucose cross through the placenta to the baby, the baby must produce more insulin to control it. High levels of glucose along with high levels of insulin (hyperinsulinism) cause increased growth (macrosomia) and fat storage, meaning the baby will grow bigger and fatter than they should. It can also cause polyhydramnios (increased fluid levels).

Large babies may present physical difficulties at delivery, increasing the rates of caesarean section, birth trauma and injury (such as shoulder injury from vaginal delivery). There is also an increased risk of stillbirth and preterm birth.

After birth, babies are more likely to be admitted to a neonatal intensive care unit with hypoglycemia, jaundice or breathing difficulties. Long term, babies born with hyperinsulinism are also known to have an increased risk of developing obesity and type 2 diabetes.

What are the warning signs of gestational diabetes?

Most women don’t know they have GDM until it is detected with screening, so booking and attending antenatal screening is important for mothers-to-be.

A complication is that some of the symptoms of GDM are also common pregnancy symptoms, including tiredness, increased urination, dry mouth and thirst, nausea, vomiting after meals, and sweet food cravings. GDM symptoms not so commonly reported as pregnancy symptoms include blurred vision, tingling in hands and feet, and urinary tract, vaginal or skin infections.

If you’re pregnant and experiencing these symptoms, it’s important to let your doctor or midwife know so GDM can be checked for.

How is GDM treated?

Although women cannot completely get rid of gestational diabetes while pregnant, treatment is known to improve both maternal and fetal outcomes. Treatment includes self-monitoring of blood glucose levels, dietary and exercise changes, and medication if needed. There is no conclusive evidence that gestational diabetes is caused by diet, but hyperglycemia can be lowered naturally through exercise and diet.

Stable blood glucose levels can be achieved with diet by controlling carbohydrate intake according to its glycemic index (GI)(i.e. how fast the food releases sugar into the blood). Individual tolerance to certain foods changes over pregnancy, so careful monitoring of blood sugar levels after meals will help to identify this. Portion size, the regularity of meals and drinking plenty of water each day will also help.

You can also take up some physical activities. Exercise causes the muscles to take in more glucose, naturally lowering blood glucose levels. After exercising the muscles also remain more sensitive to insulin. So, exercise reduces both blood sugar levels and insulin resistance.

Low blood sugar and GDM

GDM can also cause low blood sugar, particularly if medication (tablets or insulin injections) is taken or in women who do not eat enough to meet the extra needs of pregnancy. Women may also alternate between the two conditions of hyper- and hypoglycemia, so regular snacks may be needed. If sugar levels remain high or unstable, insulin injections or oral medication may also be required.

Mothers with GDM will experience more clinic appointments with obstetricians, midwives, specialist nurses and dieticians who will all help in successful management. Increased monitoring of the baby's size and amniotic fluid levels will also be recommended.

Safely monitor your pregnancy

Navigating pregnancy can be a stressful and overwhelming process, especially in between all the other responsibilities of Hong Kong life. At OT&P Annerley, our midwives help ease that burden for you by providing the in-depth guidance, education and checks required for worry-free childbirth. We’ll be with you every step of the way from pregnancy, delivery and up to eight weeks after birth. We also provide a wide variety of antenatal classes to ease you into the pregnancy journey. Get in contact with us today to learn more.