Induction for gestational diabetes: what’s the evidence?

Is there any evidence of benefit for induction for gestational diabetes?

That’s a question I hear a lot. Women who have been told that they have gestational diabetes are often also offered early induction of labour. But is there any evidence of benefit for this?

I looked at this question when I updated my 2018 book Inducing Labour: making informed decisions. In there, I talked about women who are ‘said to have’ developed gestational diabetes.

I use the words ‘said to have’ “…because the diagnosis of gestational diabetes is not at all clear cut. The guidelines, tests and cut-off points used to decide whether a woman has gestational diabetes differ widely between countries and areas. This is incredibly confusing and unhelpful…” (Wickham 2018).

I’m not going to look at that in more depth in this post, but I’ve written a bit more on this here. If you want to know more about gestational diabetes, my favourite resources include this blog post and Rachel Reed has also recorded a great podcast on this topic.

What I am going to do in here is to look at whether there is evidence to support induction for gestational diabetes.

 

Recommendations and risk

Many midwives report that some of their obstetric colleagues recommend induction for gestational diabetes.

Sometimes, gestational diabetes is the only issue (or risk factor). Sometimes, women are told that that induction is recommended because they have other risk factors or complications too.

Sadly, I often hear that, if women decline induction based on one risk factor, perhaps because they are aware that there is no evidence of benefit, other issues are then (or later) presented as justifying induction in addition to the first reason.

This is such an important issue that I want to explain it before we look at the evidence for gestational diabetes alone.

Having several ‘risk factors’ doesn’t necessarily justify induction. That’s especially the case if there’s no evidence to show that induction is beneficial for each of those risk factors on their own. Adding them up doesn’t make a justification for intervention which isn’t justified for individual risk factors.

There’s another issue to be aware of as well. There’s a difference between having an actual problem and being perceived to be “at higher risk.” Don’t forget that very few of those who are “at higher risk” will go on to have an actual problem.

So, as I wrote in In Your Own Time, being said to be “at higher risk” isn’t necessarily a good reason for intervention. Medical problems might justify intervention, although that’s always up to the person whose body it is. But being “at higher risk” isn’t the same as having pre-eclampsia or having a baby who is experiencing a specific health problem in utero. This can be a complex area, so good, woman-centred, educated, experienced health professionals can be invaluable here. If you feel you need more information that you are getting from your care provider, ask for an appointment with a consultant midwife. You will be able to talk through the evidence and your individual situation.

 

But what about the evidence?

But what about the evidence for induction for gestational diabetes?

Well, there are two really important things to know about the research in this area. The most important thing we can say is this:

There is no evidence showing that induction of labour is beneficial for women with gestational diabetes.

As I will discuss below, there has been only one small trial that looked at this area. It found no difference between women whose labours were induced and women who waited for their labour to start spontaneously.

The second key point is also important.

There is a lack of good research in this area.

The only trial that has been done is small, and wasn’t that robust. It’s possible that a larger trial might show a difference. A larger and better research study might show that there are benefits to waiting. It might show that there are benefits to induction. Or, like the current small trial, it might show that there is no difference between the options. In the meantime, as above, we have no evidence to justify intervening.

 

What do the World Health Organization and NICE say?

In 2018, the World Health Organization (WHO) updated their guidelines on Induction of labour at or beyond term.

The WHO recommend that induction of labour should not be offered for gestational diabetes unless there is evidence of other abnormalities occurring, such as abnormal blood glucose levels. Even then, as above, there is no evidence that induction is beneficial.

In the UK, the relevant NICE guidelines state that induction (or elective caesarean) should generally not be considered before 40⁺⁶ weeks for women with gestational diabetes. The exception to this is if either the mother or baby is experiencing complications. So, as above, if there is an actual problem. But also as above, this should be an actual complication or medical problem and not just a risk factor.

What about that study?

The most recent Cochrane review only found one study. This research included 425 women and their babies and compared induction of labour with waiting for spontaneous labour.

The results showed that induction made no difference to the outcomes.

“The findings of this trial highlighted no clear difference between the babies of women in either group in relation to the number of large babies, baby’s shoulder getting stuck during birth or babies with breathing problems, low blood sugar and admission to a neonatal intensive care unit. No baby in the trial experienced birth trauma. In the group of women whose labour was induced, there were more incidences of jaundice in the babies.” (Biesty et al 2018).

The summary: There is no evidence to support induction of labour in women with gestational diabetes and no other complications.

 

The problems in researching

The authors of the included study noted some of the problems in researching this area. These included, “…the inherent inaccuracy of sonographic EFW [estimated fetal weight], especially in cases of suspected macrosomia [large baby].” (Berger & Melamed 2014).

They also noted that, “The available studies are underpowered to address the effect of elective delivery on the risk of fetal death, which is probably one of the main reasons for adopting an approach of routine elective induction based on gestational age alone. Other clinical factors such as the type of diabetes, degree of glycemic control, degree of growth asymmetry (e.g. AC/FL ratio) and Bishop’s score have not been incorporated in the management protocols investigated in these studies.” (Berger & Melamed 2014).

In short, we don’t have good evidence on which to base a recommendation of induction for gestational diabetes.

 

Problems in care settings

The authors of the same study highlight another very real problem which stems from the lack of good studies.

“The absence of such evidence has also resulted in a considerable variation in the recommendations of the different societies. We believe that with a lack of solid evidence to justify routine intervention based on any type of threshold, the decision on elective delivery should be made on an individual basis, taking into account a number of clinical factors including gestational age, sonographic and clinical estimated fetal weight, type of diabetes, degree of glycemic control, obstetrical history of the individual patient (e.g. a history of stillbirth) as well as parity and cervical status. The potential benefits and risks of elective delivery should be discussed with the patient, and patient preference following such a discussion should also be included in the final decision on elective delivery.” (Berger & Melamed 2014).

 

More recent research

A more recent paper by Jabak & Hameed (2020) confirms that this problem continues.

There “…have been no randomized control trials behind these recommendations. The aforementioned women have comparable outcomes to pregnant women who are not affected by diabetes and can be considered as low risk till any evidence is found.” (Jabak & Hameed 2020).

But the authors go further than noting that there is no evidence for induction for gestational diabetes. They also criticise the idea that women with well-controlled gestational diabetes should be told they need to give birth in hospital.

“With the lack of current evidence, we find it difficult to recommend mothers with well-controlled gestational diabetes to give birth in obstetrics led unit with continuous fetal monitoring and deny them a chance to have home birth or birth in midwifery-led birth units. There is an urgent need to conduct large scale randomized controlled trials to establish evidence for or against this recommendation.” (Jabak & Hameed 2020).

 

Sometimes, even when there is no evidence to support intervention, some people suggest that it is still better to intervene “just in case.” But intervention can cause harm, especially when it is offered for something that affects a good many women. We know that induction causes avoidable harm, including increasing the chance of caesarean. We know that induction is associated with more interventions and leads to more adverse outcomes. We know that women aren’t given adequate information about induction. And we know that there are significant benefits to awaiting spontaneous labour.

 

Induction increases caesarean

In a 2022 study, researchers in Australia carried out a population-based study comparing induction of labor with expectant management in women with gestational diabetes and without specific medical conditions.

Seimon et al (2022) looked at data from “women with GDM, but without medical conditions, who had a singleton, cephalic birth at 38–41 completed weeks gestation, in New South Wales, Australia between January 2010 and December 2016. Women who underwent IOL at 38, 39, 40 weeks gestation (38-, 39-, 40-induction groups) were compared with those who were managed expectantly and gave birth at and/or beyond the respective gestational age group (38-, 39-, 40-expectant groups).”

“Of 676 762 women who gave birth during the study period, 66 606 (10%) had GDM; of these, 34799 met the inclusion criteria. Compared with expectant management, those in 38- (adjusted odds ratio (aOR) 1.11; 95% CI, 1.04–1.18), 39- (aOR 1.21; 95% CI, 1.14–1.28) and 40- (aOR 1.50; 95% CI, 1.40–1.60) induction groups had increased risk of caesarean section. Women in the 38-induction group also had an increased risk of composite neonatal morbidity (aOR 1.10; 95% CI, 1.01–1.21), which was not observed at 39- and 40-induction groups. We found no difference between groups in perinatal death or neonatal intensive care unit admission for births at any gestational age.”

Their conclusion was that, “In women with GDM but without specific medical conditions and eligible for vaginal birth, IOL at 38, 39, 40 weeks gestation is associated with an increased risk of caesarean section.”

 

All of this means that we need to think very carefully about whether induction is truly justified. There is no evidence showing that induction is beneficial for women with gestational diabetes.

First do no harm.

 

For more information about induction of labour, you might like to see my induction resources hub. I have also written two books on this topic:

In Your Own Time

Inducing Labour

If you’re a midwife or birth worker, you might like to sign up to my newsletter so that, like thousands of other people, you can get my updates on birth-related research and thinking sent straight to your email inbox.

 

Berger H & Melamed N (2014). Timing of delivery in women with diabetes in pregnancy. Obstet Med 7(1):8-16. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4934937/

Biesty LM, Egan AM, Dunne F et al (2018). Planned birth at or near term for improving health outcomes for pregnant women with gestational diabetes and their infants. Cochrane Database of Systematic Reviews 2018, Issue 1. Art. No.: CD012910. DOI: 10.1002/14651858.CD012910 https://www.cochrane.org/CD012910/PREG_planned-birth-or-near-term-pregnant-women-gestational-diabetes-and-their-infants

Jabak S & Hameed A (2020). Continuous intrapartum fetal monitoring in gestational diabetes, where is the evidence? The Journal of Maternal-Fetal & Neonatal Medicine https://doi.org/10.1080/14767058.2020.1849117

Seimon RV, Natasha N, Schneuer FJ et al (2022), Maternal and neonatal outcomes of women with gestational diabetes and without specific medical conditions: an Australian population-based study comparing induction of labor with expectant management. Aust N Z J Obstet Gynaecol. https://doi.org/10.1111/ajo.13505

Wickham S (2018). Inducing Labour: Making informed decisions. Avebury: Birthmoon Creations.

Wickham S (2021). In Your Own Time: how western medicine controls the start of labour and why this needs to stop. Avebury: Birthmoon Creations.

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