Small and 'healthy' weight gains before pregnancy could double diabetes risk: Study

The new results from Queensland University, Australia are the first to show the importance of weight stability regardless of Body Mass Index (BMI) and its link to gestational diabetes mellitus (GDM), a form of the disease found in pregnant women.

Maintaining a consistent weight in the lead up to pregnancy can evidently halve the likelihood of GDM – the risks of which include stillbirth and obesity or type 2 diabetes in the child.

Professor Keith Godfrey from the Medical Research Council Lifecourse Epidemiology Unit at the University of Southampton, UK, commented: 

"It is now widely recognised that excessive weight gain before and during pregnancy is associated with long term health risks for the offspring, notably of obesity and associated disorders including raised blood pressure and cardiovascular disease. These risks to the offspring’s later health are even greater if the mother has higher blood sugar levels during pregnancy, and particularly if she develops gestational diabetes. Measures that prevent gestational diabetes are therefore of major public importance, for both the mother and her baby."​

Dr. Carrie Ruxton of Nutrition Communications agreed, saying: 

"While this is an observational study which can't prove cause and effect, it backs up other evidence that weight gain and inactivity can lead to insulin resistance. This is a risk for gestational diabetes - a condition that causes large birth weight babies and which sometimes develops into type 2 diabetes for the mother.​

"Women planning a pregnancy should ensure that they are physically active and within a normal body weight range. They then should be given guidelines on what is a reasonable weight gain during pregnancy. Pregnant women don't need to eat for two and exercise should be encouraged until late in pregnancy unless contraindicated by medical conditions. Women should also take a daily supplement of folic acid and vitamin D when planning a pregnancy as the latter may have a positive impact on diabetes risk."​

The risks associated with overweight and pregnancy are well recorded; a study​​ early this year compiling research from expert groups throughout the world found an ‘absolute consensus’ that overweight and obesity from the point of conception and throughout pregnancy typically triples the chance of the child becoming obese itself.

Study details​

The study took 3,111 participants, all of whom were previously part of a cohort of the ‘Australia Longitudinal Study on Women’s Health’, which recorded health patterns in over 58,000 women starting in 1996.

The participants, whose average age during the study was 20, were measured for pre-pregnancy weight changes and pre-pregnancy BMI. These results were used to associate alterations in weight with risk of GDM. 

Between 2003 and 2012, 2229 cases of GDM were found in 5242 pregnancies. Unsurprisingly, participants with obese BMIs had a far higher incidence of contracting the disease than those with normal BMIs.

However, changes before and during pregnancy in weight were associated with increased GDM risk, regardless of whether the BMI went over a healthy level. In other words, even small weight gains in which a woman maintains the same weight category can strongly increase the chances of developing GDM.

Women whose BMI rested within a healthy weight band but increased by up to 2.5% per year, generally doubled the chance of GDM, with some changes increasing the risk by almost triple.

Akilew Adane, chief researcher on the study, was quoted as saying “It's important for women and their clinicians to be aware that, even in the healthy BMI range, gaining a kilogram or two a year can be a health risk." ​

"For instance, a 60-kilogram, 166-centimetre woman is in a healthy BMI range, but if she gains 1.14kg each year for seven years (about two per cent of her body weight) her risk of gestational diabetes would double compared to a woman whose weight remained stable.​

"It's likely that women who continue to gain weight through early adulthood may experience a modest, progressive insulin resistance, which is further exacerbated by pregnancy, even though their weight is still within the normal range."​

Source: Diabetes Research and Clinical Practice​
Published 2017; DOI: http://dx.doi.org/10.1016/j.diabres.2016.12.014​​​
"Pre-pregnancy weight change and incidence of gestational diabetes mellitus: A finding from a prospective cohort study"​
Authors: Akilew Awoke Adane, Leigh R. Tooth, Gita D. Mishra