Lifestyle changes ineffective at reducing risk of gestational diabetes in pregnant women

Discussions surrounding healthy weight gain during pregnancy is often neglected during antenatal care. Too often, lifestyle factors contributing to a healthy pregnancy weight (such as nutrition, exercise and sleep) are not considered.  Historically, women have not been weighed during routine checkups with midwives and obstetricians. Exacerbating the issue, ‘talking about weight’ has been described as a challenging activity amongst professionals.

Considering the risk of the gestational weight gain (GWG) can independently increase the risk of developing gestational diabetes mellitus (GDM) by up to 53%,¹ monitoring and discussing GWG is a critical component of the standard healthcare plan. Sixteen percent of pregnant women will develop GDM² with prevalence increasing globally.³

Gestational diabetes mellitus increases the risk of pregnancy and birth complications. Such risks include pre-eclampsia, emergency caesarian section or having an oversized baby.⁴  Women diagnosed with GDM also have a 7 to 12 fold increased risk of developing type 2 diabetes later in life.⁵ Consequently, nations around the world have programs in place to prevent excessive GWG and (potentially) GDM. The question is, which of these is most effective?  

Monash Nutrition researcher Christie Bennett is attempting to resolve this question. Christie, in collaboration with researchers from Monash University, The Hudson Institute of Medical Research, Lanzhou University and Zhejiang University, conducted a systematic review and meta-analysis of randomised controlled trials. These trials tested the interventions designed to prevent excessive GWG and ergo, GDM. As a result, the team was able to comprehensively evaluate the global impact of these intervention programs and examine if the effects differed by maternal BMI or ethnicity.

Reviewing a suite of results from randomised controlled trials (found in seven international and three Chinese databases), results were observed in reducing the incidence of GDM. Firstly, single behaviour interventions designed to reduce excessive GWG (in this case diet and physical activity) were more effective than standard antenatal care (i.e. no intervention at all). Dietary interventions reduced GDM risk by 44% and physical activity interventions reduced GDM risk by 38%. Secondly, the combination of diet and physical activity was deemed no more efficient than standard antenatal care. Despite the known relationship between sleep, obesity and diabetes,^{6, 7} the studies included in the analysis did not assess the influence of sleep interventions on GWG or GDM. While sleep is an independent and modifiable risk factor for obesity and diabetes in children and adults, we don’t know how important the sleep link is in pregnancy.

It was found, (upon analysing data on a nation-by-nation basis) that the efficacy of these interventions varied by geographical region. Physical activity interventions from Southern Europe reduced GDM risk by 37%.  In contrast, diet and lifestyle interventions conducted in Asia resulted in a 62% and 32% reduction in GDM respectively. In regions such as America, Australia and other parts of Europe there was no reduction in the incidence of GDM. Population groups that are culturally homogenous such as China and Spain (with lower levels of immigration), demonstrated consistent responses to interventions, with higher rates of efficacy. When assessing populations in countries such as Australia or the United States of America (which have higher levels of immigration) the results were inconclusive. Christie suggests that these observations are ‘likely a combination of cultural behaviours and expectations as well as genetics’.

The greater a woman's pre-pregnancy body mass index (BMI), the greater the risk of GDM.⁸ The meta-analysis confirmed that interventions were less effective in women with a high pre-pregnancy BMI. This may be due to potential underlying insulin resistance pre-conception (which is compounded by normal progression of insulin resistance during pregnancy). Given these findings, women (where appropriate) seeking to fall pregnant should receive guidance around diet and physical activity to safely attain a healthy BMI prior to conception.

Clinical practice and health initiatives aimed at managing GWG and preventing GDM are more effective when targeting a single behaviour (such as diet or exercise) rather than a combination. When combined as an overall lifestyle change, these interventions are no more effective in reducing the risk of GDM. Changing habits of both physical activity and diet simultaneously may (potentially) be too difficult when contextualised by an overlay of physical and psychological adaptions required by being pregnant.⁹ Ergo, it is recommended that practitioners should adopt a ‘women-centric’ approach. The broader context of a woman's life should be considered when planning and providing pregnancy care. This ensures that a women’s emotional, psychological, social, physical and cultural well-being is considered and respected.

This research has important implications for clinical practice and health initiatives in managing GWG. As this meta-analysis indicates, worldwide interventions designed to reduce excessive GWG that target single behaviours reduce the incidence of GDM. However, regional differences indicate that other factors (either physiological and/or behavioural) must be taken into consideration when planning GDM prevention strategies. Subsequently, a ‘one size fits all’ approach to GDM prevention is not supported.

As commented by Christie, the next steps for the team will require a ‘look into ways to reduce excessive GWG through various novel methods, such as antenatal medical team training and resource provision’. For Christie, the relationship between GDM and sleep will be her prime focus of interest.

Image credit: Jordan Bauer via Unsplash

More Information

This research was conducted in collaboration with Lanzhou University and Zhejiang University.

Read the full article in Diabetes Research and Clinical Practice here.

Christie Jane Bennett, Ruth Elizabeth Walker, Michelle Louise Blumfield, Stella-May Gwini, Jianhua Ma, Fenglei Wang, Yi Wan, Hayley Dickinson, Helen Truby, (2018) “Interventions designed to reduce excessive gestational weight gain can reduce the incidence of gestational diabetes mellitus: A systematic review and meta-analysis of randomised controlled trials”, Diabetes Research and Clinical Practice, https://doi.org/10.1016/j.diabres.2018.04.010

Christie Bennett is a PhD Candidate at the Monash University Department of Nutrition, Dietetics and Food. Her main areas of research are sleep in pregnancy and the link between gestational weight gain and glucose tolerance. You can follow Christie on Twitter via @Bennett_CJ1.

Stay up to date with the Monash University Department of Nutrition, Dietetics and Food on Twitter via @MonashNutrition.

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