Keeping Weight Stable After Gestational Diabetes Is Beneficial

Becky McCall

March 16, 2018

LONDON — High levels of weight gain after diagnosis of gestational diabetes puts women at increased risk of complicated births, including a greater risk of Cesarean section, shows a new study presented here at the Diabetes UK Professional Conference 2018.

"Women who gained excessive weight throughout pregnancy were at greater risk of having a Cesarean section and a lower chance of normal delivery, and also more likely to deliver a baby of excessively high birth weight," said Claire Meek, MD, PhD, from the Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge, UK, who reported the results.

By comparison, women who had gestational diabetes but did not gain weight during pregnancy had better short- and long-term health benefits. "Broadly, they did better, with fewer C-sections, and more normal deliveries. These women, regardless of glucose control or starting body mass index, all did better," she said.

This is believed to be one of the first studies to look specifically at the impact of weight gain after a diagnosis of gestational diabetes.

Coauthor Catherine Aiken, MD, also from the University of Cambridge, explained that "there are no targets to help women manage their weight after diagnosis [of gestational diabetes]. The results of this study suggest that keeping weight stable after diagnosis may be extremely beneficial for women and their babies."

Session moderator, Anne Dornhorst, MD, an endocrinologist at Imperial College Hospital, London, UK, said the problem in the UK is that women with gestational diabetes are not routinely weighed.

In fact, women are usually only weighed once during pregnancy, at their first antenatal 'booking in' appointment (at around 6 week's gestation). She cautioned that not all women with gestational diabetes may necessarily need to keep their weight stable — it depends on what they weighed to begin with and how much weight they have put on during the pregnancy.

Late Pregnancy Weight Gain the Worst

The retrospective observational study by Meek and colleagues evaluated 546 women with gestational diabetes who gave birth in the Cambridge University Hospitals NHS Foundation Trust in 2014–2017. Mean maternal age was 34 years and mean pre-pregnancy body mass index was 28.8 kg/m2. The effect of gestational weight gain upon pregnancy outcomes was assessed using multivariate logistic regression analysis.

Higher total gestational weight gain was associated with increased risk of large-for-gestational-age infants [LGA] (odds ratio [OR], 1.08; P < .001) and reduced risk of small-for-gestational-age infants (OR, 0.93; P < .01). Furthermore, increased gestational weight gain was associated with increased risk of Cesarean delivery (OR, 1.06; P < .001) and fewer vaginal deliveries (OR, 0.95; P < .001).

In particular, the researchers found that women who gained excessive weight later in pregnancy (28–36 weeks gestation, n = 144) were more likely to have difficult labors, with interventions including forcep and instrumental delivery (OR, 1.18; P < .05), and the effects on baby were greater, with a higher risk of LGA infants (OR, 1.17; P < .001).

They also needed a higher long-acting insulin dose at 36 weeks (OR, 1.42; P < .001) and had higher postpartum glucose concentrations (2-h post-load) (OR, 0.12; P < .05).

Meek stressed the beneficial effects of controlling late gestational weight gain.

"In those patients who kept their weight stable, they gained just under 1 kg. The rates of LGA are very different between those who kept their weight stable and those who gained weight in the late stage [4.3% vs 16.7% respectively]."

"Rates of vaginal delivery were also very different [53.2% vs 36.0%], and likewise instrumental delivery [8.5% vs 22.0%]."

She added that the baby was also at a higher risk of being overweight or obese and developing type 2 diabetes later in life if maternal weight was uncontrolled after the diagnosis of gestational diabetes. "These risks can be reduced by careful blood glucose control during pregnancy, which is achieved by dietary change or with medication such as insulin," she noted.

Little Advice on Weight After GDM Diagnosis: Should We Intervene?

Meek said many women already have substantial weight gain by the time of gestational diabetes diagnosis at 28 weeks. What drove her interest in the topic was: "Ultimately, I wanted to know whether there was any point intervening at this stage?"

Being overweight/obese prior to pregnancy makes women more susceptible to gestational diabetes, but "there are many women who are not overweight or obese prior to pregnancy but gain lots of weight in the first few months and get gestational diabetes," she noted.

Women are also at increased risk of developing gestational diabetes if they have had the condition before, had a large baby in a previous pregnancy, or have a family history of type 2 diabetes.

"Essentially we know high levels of weight gain are a risk factor for gestational diabetes, but this study adds that it is possible to change this," she stressed.

However, there is currently little guidance on weight control in gestational diabetes, she noted.

The National Institute for Health and Care Excellence (NICE) in the UK recommends diet and exercise in women with gestational diabetes, and provision of post-partum lifestyle advice.

The US Institute of Medicine recommends weight gain according to pre-pregnancy weight, but these guidelines are for healthy women, not for those with gestational diabetes.

Dornhorst reiterated that women with gestational diabetes, which is diagnosed at around 28 weeks, aren't routinely weighed, at least not in the UK.

"If we are going to advise on diet and they do see a dietitian, then the dietitian needs to know how much weight they have gained since booking [week 6], and should be able to provide advice on what is safe weight gain [or not]."

Dornhorst cautioned that it could be hazardous for some women to restrict calorie intake. "We've got women with gestational diabetes who come in at all different weights. Some are not overweight, and we don't want these women to eat too little just to avoid insulin, but there are others who eat enough for four and don't need to gain weight."

Meek acknowledged her results are "preliminary" but said they "suggest an opportunity for women to improve their health during pregnancy, and to have healthier, safer pregnancies and babies if they keep their weight stable after diagnosis of gestational diabetes."

However, she pointed out that larger studies are needed to confirm these findings and determine exactly what the target weight should be in both early and late pregnancy. "Other research needs to address how many calories a woman should eat to achieve these targets."

Meek's future work will aim to answer these questions. She will soon start the Dietary Intervention in Gestational Diabetes (DIGEST) study to look at this topic in more detail.

Meek has received funding from Diabetes UK. Dornhorst has reported no relevant financial relationships.

Diabetes UK Professional Conference 2018. March 15, 2018; London, UK. Abstract A38.

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