You’re nearly there in terms of birthing your baby…but in terms of tests, there’s still more to consider during your third trimester. Here’s what you can expect.
GLUCOSE TOLERENCE TEST (GTT)
During weeks 24-28 of pregnancy, some women may develop gestational diabetes which affects 12-14% of pregnant women. Gestational diabetes affects thousands of pregnant women therefore it is important to have the glucose tolerance test (GTT) for the health and safety of you and your baby.
What is gestational diabetes?
Gestational diabetes can occur in pregnant women when the hormones from the placenta cause your cells to become insulin resistant.
Women will usually develop gestational diabetes towards the end of the second trimester or early in the third, although it can sometimes happen earlier. Gestational diabetes will usually go away after the baby is born.
Some women with an increased risk of developing gestational diabetes include:
- Women over 40 years old
- Women who have a family history of type 2 diabetes or have had a family member develop gestational diabetes
- Women who are above the healthy weight range, have had elevated blood glucose levels in the past or had gestational diabetes in the previous pregnancies
- Women from certain ethnic backgrounds such as Melanesian, Polynesian, Southeast Asian, Middle Eastern, Aboriginal or Torres Straight Islander
However, women with no known risk factors can still develop gestational diabetes, so it’s important every woman gets the glucose tolerance test as left undiagnosed may affect you or your baby.
How to prepare for the glucose tolerance test?
Before the test your will need to fast for a period of 8-10 hours. Do not eat or drink anything (except water) during this time.
If you have eaten in the eight hours before the test or fasted for longer than 16 hours, recently experienced a period of acute illness or suddenly developed a cold or flu, it will be best to postpone your test.
What to expect during your test
When you first arrive you will receive a blood test, this is your baseline glucose level. You will then drink a 75g dose of glucose drink to be consumed within five minutes. We recommend bringing some reading material as you then are required to wait one hour before a second blood test is taken. A third blood test will then be taken after another hour wait.
The test is expected to take about two hours and 45 minutes so make sure to give yourself plenty of time to complete the whole procedure. Once the test is complete you are free to resume your regular activities and consume food and drink.
Your results will take approximately two business days and will be sent to your doctor.
GROUP B STREPTOCOCCUS (GBS)
Towards the end of your pregnancy, around 35 to 37 weeks, your doctor will discuss with you about getting the group B strep test.
What is group B strep?
Group B Streptococcus (GBS) is a type of bacteria that lives in our bodies. It is very common and if you happen to carry it while healthy it is usually not a health concern or a disease that needs to be treated. It is not a sexually transmitted disease.
When giving birth around 20% of women will have group B strep in their vaginas, however it is important to know carrying GBS is different to being infected with GBS and if you are infected you will need to receive treatment (normally antibiotics) as GBS can make you and your baby very sick.
The main concern if you carry GBS is the chance of passing it onto the baby during a vaginal birth. While many babies may also carry GBS and will remain well, a small number (about 1 in 200) can become very sick with infections such as pneumonia, blood infections (sepsis) or meningitis and will require urgent treatment.
The test
The GBS test is done at 35 to 37 weeks of pregnancy and involves taking a swab of the inside of the vagina. The test is done this late into the pregnancy as any earlier will not be a good indication to your condition at birth as the bacteria can come and go.
GBS infection risk factors
Some babies have a higher risk of contracting a GBS infection. Those with a higher risk include:
- Babies born prematurely
- If you had a previous baby with a GBS infection
- You have a fever greater than 38°C during labour
- Your baby is born more than 18 hours after your waters break
- A urine test during pregnancy or the swab detected GBS
Can GBS infection in my baby be prevented?
While GBS infection can not be 100% prevented, if you test positive or have any of the above risk factors your doctor will likely recommend that you receive intravenous antibiotics when you go into labour, as the antibiotic is most effective two to four hours before your baby is born. The antibiotics are often penicillin so talk to your doctor about alternatives if you have a penicillin allergy.
What if I’m planning a caesarean?
Women planning a caesarean birth do not need to have antibiotics as the baby will not pass through the vagina therefore you can not pass on the bacteria. However, it is recommended you consider having the test even if you are planning a caesarean incase your waters break or your go into labour early.
Your baby will be monitored for the first few days after birth for signs of infection if you received antibiotics during labour.
ANTI-D INJECTION
Blood types are categorised in two ways – ABO and Rhesus. There are four main blood groups: A, B, AB, and O and with each blood type a person can be either positive or negative, which indicates the Rhesus factor. While pregnant if you are part of the population that has negative blood you will need to receive the Anti-D injection during the third trimester of your pregnancy.
What is the Rhesus factor?
The Rhesus (Rh) factor indicates whether your blood contains a protein known as the ‘D antigen.’ If you have positive blood you have the Rhesus factor meaning your blood contains the protein, whereas if you are negative you lack the Rhesus factor.
Having negative blood is not an issue and only becomes a concern when you are pregnant and your partner is Rh positive. This means that there is a chance your baby will be Rh positive, which can become a problem if any of the baby’s blood enters the mother’s bloodstream.
Why do I need the Anti-D injection?
During pregnancy there are different ways a baby’s blood may enter a mother’s bloodstream and if Rh positive blood enters an Rh negative bloodstream, the body would recognise the Rh factor as foreign, causing the body to produce antibodies against the baby’s blood. While this is not a concern for the baby, it can be an issue for future pregnancies.
In future pregnancies with an Rh positive baby, the mother’s immune system will likely produce more antibodies which can cross into the placenta and destroy the baby’s blood cells. If this happens it can cause a series condition called haemolytic disease which can lead to anaemia and jaundice, in serve cases it can cause brain damage or even still birth.
What is the Anti-D injection?
The Anti-D injection is given to Rh negative women with Rh positive partners at weeks 28 and 34 of pregnancy. Anti-D neutralises any blood cells of you Rh positive baby before your body has a chance to create antibodies.
When your baby is born, blood will be taken from the umbilical cord to test their blood. If it comes back Rh positive you will be given a third dose of Anti-D.
The Anti-D injection is safe for both mother and baby and you will need to have the injections during each pregnancy. As this is a blood injection your doctor or midwife will test you to confirm you have Rh negative blood.
It is important to have these injections during each pregnancy because if a woman has produced Anti-D antibodies in a previous pregnancy the injections are no longer useful. If a women has developed anti-bodies all future pregnancies will be monitored much closer as will the baby once it is born.
