What is Gestational Diabetes?
It can be defined as high blood sugar diagnosed for the first time during pregnancy and it usually resolves after birth. It can happen at any stage during pregnancy, but is commonly diagnosed during the second or third trimester.
Gestational diabetes results in high blood sugar that can affect pregnancy and the baby.
What causes gestational diabetes?
Researchers have not yet discovered what causes diabetes during pregnancy in some women. However, pregnancy causes hormonal changes that impair sugar metabolism. Such hormones include insulin that controls the blood sugar levels, and hormones produced by the placenta (placental lactogen). Obesity or excessive weight gain during pregnancy also decreases the sensitivity of body cell receptors to insulin, thus resulting in a condition called Insulin Resistance (and therefore, increased blood sugar levels).
What are the risks to my baby?
The risks may be divided into three parts: problems that affect the baby before birth (antepartum), during delivery, and after birth (postpartum).
Antepartum (before birth):
Congenital abnormalities (abnormalities a baby is born with) such as heart defects, neural tube defects, skeletal defects, and less commonly sacral agenesis. These are resultant of uncontrolled high level of blood sugar during conception or when organs are developing.
Fat baby (macrosomia): A baby becomes fat because the excess blood sugar is converted and stored as fat in the fat tissue (adipose tissue).
Death of a baby while in the womb (intrauterine death): The mechanism of how gestational diabetes causes death of an unborn child is not understood, but the two can be linked when all other possible causes are ruled out.
Polyhydramnios (excess fluid (amniotic fluid) surrounding the baby in the uterus) can cause premature labor and a difficult delivery.
Preterm birth (when a baby is born before 37 weeks of pregnancy): The doctors may decide to deliver the baby before time, preventing further complications when the diabetes is not well controlled.
During delivery:
Shoulder dystocia: Because the baby is fat (macrosomia-normal sized head but big body), the delivery becomes difficult and with assistive tools the baby’s collar bone or upper arm may be fractured. The baby may also not be able to move the shoulders, arms, hands, and fingers, and may even be brain damaged because of the injury to the nerves responsible for these functions.
After birth (postpartum):
Low blood sugar (hypoglycemia): This condition is caused by high levels of insulin that is secreted in response to the high level of blood sugar. It is further made worse by the immaturity of the newborn enzymes (proteins that speed up the metabolic processes).
Polycythemia: A disease in which there are many red blood cells in the bone marrow and blood causing blood to thicken which may result in Hyperbilirubinemia. Hyperbilirubinemia is condition that causes the yellowish discoloration of the baby’s skin, eyes, and hands.
Respiratory distress syndrome (condition that causes difficulty in breathing) which is caused by being born early or prematurely before the lungs are fully developed.
Still birth: Death of a baby after 20weeks of pregnancy.
A baby may also develop diabetes mellitus and obesity later in life.
What are the symptoms of gestational diabetes?
Typically, gestational diabetes does not present with symptoms, but there are risk factors that can cause healthcare professional to be suspicious and do blood sugar tests for diagnosis. These risk factors include:
A woman who has been previously diagnosed with gestational diabetes
Mothers over forty years of age
Mothers with high body mass index (BMI) of more than forty, or over 90 kg in weight
First-degree family history of diabetes mellitus
History of typical diabetes symptom such as frequent passage of urine, excess thirst, vaginal thrush
Mother that has had a fat baby before
Previous still birth of unknown cause
Mother that has repeatedly been found with sugar in urine (glucosuria)
A woman that has been diagnosed with a condition called polycystic ovarian syndrome
When any of these risk factors are discovered through medical history, a doctor may run either of the two blood sugar tests: fasting blood glucose or random blood glucose. However, if in doubt of the result obtained, he may offer an oral glucose tolerance test (OGTT). These are called screening tests and are usually done between 24 and 28 weeks of pregnancy, and in a case where the above listed factors are not present.
A diagnosis of gestational diabetes is made when fasting blood glucose level is more than 6.9mmol/l or when random blood glucose level is more than 11.0mmol. If OGTT was done, the blood glucose level equal or more than 7.8mmol after 2hours is diagnosed as gestational diabetes.
How can I prevent gestational diabetes?
There are no guarantees in preventing gestational diabetes but maintaining a healthy lifestyle before pregnancy can help. Below are few health tips considered helpful and they may also prevent the recurrence of gestational diabetes in subsequent pregnancies.
Maintain healthy diet
Keep active
Start pregnancy at a healthy weight
Avoid gaining more weight than recommended
Can gestational diabetes be treated?
While gestational diabetes may be a concern for poor perinatal outcome if not managed, it can be controlled and result in healthy pregnancy and safe childbirth. A big part of controlling gestational diabetes lies in lifestyle modification (as discussed under prevention). Also, regular blood sugar monitoring is recommended, and this is usually done during the routine antenatal care appointments. Medical intervention may be added, if necessary.
Take home message
Gestational diabetes, may be controlled and treated during pregnancy, resulting in healthy pregnancy and healthy baby. It disappears after pregnancy.
This article is written by Dr Katleho Tau (MBChB-UKZN)
References:
1. Mayo Clinic. Gestational diabetes. [Internet]. Mayo clinic. 2022. Available from: https://www.mayoclinic.org/diseases-conditions/gestational-diabetes/symptoms-causes/syc-20355339
2. Cronje HS, Cilliers JBF, Du Toit MA, Adam Y, Adam S, Bagratee JS, et al. Clinical Obstetrics, a South African perspective. Pretoria. Van schaik Publishers. 2016
3. NHS. Gestational diabetes. [Internet]. NHS. 2022. Available from: https://www.nhs.uk/conditions/gestational-diabetes/
4. CDC. Gestational diabetes. [Internet]. CDC. 2021. Available from: https://www.cdc.gov/diabetes/basic/gestational.html
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