Gestational diabetes and the evidence around induction of labour before 40 weeks.
Between 24 and 28 weeks of pregnancy, you will be offered a GD test – screening for gestational diabetes. It can be done earlier if you have risk factors (previous gestational diabetes or a family history of type 2 diabetes for example).
In New Zealand, this is how the screening is done?
- Glucose challenge test: done in one hour, no fasting required
- You will drink a glucose-rich solution.
- Your blood will be drawn one hour later to measure your glucose level.
- Eating and drinking beforehand is permitted.
- Glucose tolerance test (GTT) done in two hours, fasting required
- If you have risk factors or your glucose challenge test is high, you will be scheduled for a fasting GTT.
- You will have your blood drawn after fasting (usually 8-14 hours).
- You will then drink a glucose solution.
- Your blood will be drawn again usually after one and two hours, to see how your body processes the sugar over time.
The glucose solution is a 350ml drink that kind tastes like Sprite – take your time drinking it. If you get sick and vomit the solution, the test will be invalidated, and you will have to do it again.
You’ve been diagnosed with gestational diabetes — now what?
Gestational diabetes can happen to anyone. It’s not your fault, and it doesn’t mean you did anything wrong.
Gestational diabetes occurs when your body can’t make enough insulin to meet the extra needs of pregnancy. The good news is that it can usually be managed effectively to keep you and your baby healthy.
Here’s what typically happens next:
- Support from a healthcare team
This may include your midwife, doctor, and a diabetes specialist or dietitian. They’ll help you create a plan that works for you.
- Blood sugar monitoring
You’ll be shown how to check your blood glucose levels at home. This helps track how your body responds to food and activity.
- Diet and nutrition
You’ll likely meet with a dietitian who will help you plan balanced meals — focusing on whole grains, vegetables, lean proteins, and controlled portions of carbohydrates.
- Staying active
Light to moderate exercise (like walking or prenatal yoga) can help your body use insulin more effectively — but always follow your care provider’s advice. - Medication, if needed
If blood sugar levels can’t be managed through diet and activity alone, you may need insulin or other medication. Talk to your LMC about your options.
- Extra monitoring for your baby
You’ll likely have more frequent checkups and ultrasounds to make sure your baby is growing well.
- After birth
In most cases, gestational diabetes goes away after baby is born. You’ll have follow-up blood tests, and your healthcare provider will discuss how to lower your risk of developing type 2 diabetes in the future.
Around 61,000 women give birth in NZ each year and about 4.9% (6.6%) of those women have diabetes. Screening for GD is recommended for all pregnant women but remember it is your choice, and you can decline any tests or screening you are not comfortable with.
Regardless of your choice of LMC, midwife, obstetrician, hospital midwives, you will be offered an induction around 38 weeks. It is standard practice in New Zealand. Why? Because if you are diabetic or have developed gestational diabetes during pregnancy, your baby may have a higher amount of body fat.
“Big baby” can increase the risk of shoulder dystocia – when baby’s shoulder gets stuck behind the mother’s pubic bone after their head has come out. Shoulder dystocia occurs in 0.7% of vaginal birth. An induction of labour is often recommended to reduce this risk.
But shoulder dystocia is unpredictable and unpreventable – In fact Te Whatu Ora’s Guideline* states that induction of labour is a risk factor for shoulder dystocia along with maternal BMI, diabetes, foetal macrosomia (baby estimated to weigh > 4.5kg), assisted vaginal birth, prolonged first or second stage of labour, synthetic oxytocin augmentation. So why would we recommend induction of labour to avoid shoulder dystocia when an induction increases the risk of shoulder dystocia??
So, when it comes to induction of labour for gestational diabetes, what is the evidence? Well, there is none. Studies have not shown a clear reduction in risk in women with well-managed GDM. On the contrary, routine induction can lead to a cascade of interventions and potential need for baby for NICU care.
Another great read is Sara Wickham’s article about induction and GDM. She outlines the lack of evidence showing that induction could be beneficial for women with diabetes. There is also a lack of good research in this area like in many others when it comes to women’s health.
The decision to induce should be made individually and not as routine. Instead, the focus should be on managing the condition, supporting and educating women and the need of interventions should be evaluated based on specific, rather than general.
https://www.sarawickham.com/articles-2/induction-for-gestational-diabetes/
If you know me, you know I am a big fan of Dr Rachel Reed work. She wrote an interesting blog on the subject as well. She emphasises that high blood glucose levels (BGLs) increase the risk of complications but there is a lack of evidence to support that diagnosis and interventions improve outcomes.
https://www.rachelreed.website/blog/gestational-diabetes-beyond-the-label
It is important to remember that hospital policy and doctor’s recommendations are not law. Make sure you make an informed decision, do your research, question the medical professionals – yes, they have knowledge, but they don’t know everything. Your body, your baby, your choice.
My name is Julia Matthews; I am a qualified doula who has completed training at the Doula Training Academy. I service West Auckland, Central and North Shore area (New Zealand).
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