Diabetes risk to mums who put on weight between babies

WOMEN who pile on the pounds between pregnancies are at greater risk of suffering a form of diabetes, say researchers.

Their study shows the chance of developing gestational diabetes mellitus (GDM) rises with weight gain between babies.

The condition is marked by high blood sugar and develops during pregnancy before usually disappearing after giving birth. It can occur at any stage of pregnancy, but is more common in the second half.

It occurs if the mum-to-be cannot produce enough insulin – a hormone that helps control blood sugar levels – to meet the extra needs in pregnancy.

Both pre-pregnancy body mass index (BMI) and weight gain during pregnancy are known risk factors for GDM, which can cause health problems for both mothers and babies.

In the latest study, researchers used data from the Medical Birth Registry of Norway on nearly 25,000 mothers with a first and second pregnancy between 2006 and 2014. The figures included BMI at the start of each pregnancy as well as any diagnosis of GDM.

The overall risk of GDM in second pregnancy was 18.1 per 1,000 pregnancies, while the BMI of more than a third of women in the study rose by more than one unit between the start of their first pregnancy and the start of their second. These women had an increased risk of developing GDM in their second pregnancy compared to women whose weight was stable.

Women who gained between one and two BMI units had a doubled risk, while the risk for those gaining between two and four units rose 2.6 times, and women gaining four or more units had a five-fold increased risk.

Gestational diabetes can cause women to have prema- ture babies and in rare cases to suffer a stillbirth.

They put themselves at greater risk of type 2 diabetes in the future, while their babies grow larger than usual and are more likely to be overweight teenagers.

The rise was highest in women who had a BMI below 25 – a score between 18.5 and 24.9 is considered normal – in their first pregnancy. This may be because putting on weight prevents insulin, which keeps blood sugar levels down, from working properly.

Women of normal weight deliver a shock to their system by putting on the pounds and this makes the body less receptive to insulin. Preg- nancy can have the same effect, meaning these women suffer a double shock that tips them over the edge into diabetes. The bodies of women who are overweight to begin with have already been subjected to what is described as insulin resistance.

More than 60 per cent of the women in the study had an interval between their first and second pregnancy of less than two years. The researchers, whose findings were published in the journal PLOS Medicine, said there was evidence of a preventive effect on GDM in overweight women who reduced their weight by two or more BMI units between pregnancies.

The authors urge doctors to take note of their findings for women who put on weight between childbirth. They should be labelled as a high- risk group based on this factor alone, they suggest.

The study states: ‘Pregnant women who increase their weight by one BMI unit from their first to second pregnancy should be closely monitored during their second pregnancy to reveal development of gestational diabetes, irrespective of pre-pregnant BMI.’

It is believed losing weight between children could protect overweight women from becoming diabetic.

Study leader Linn Sorbye, of Bergen University, said: ‘Antenatal guidelines for monitoring GDM in pregnancy should add inter-pregnancy weight change as an independent risk factor for GDM.’

An estimated 3.5 per cent of mothers to be in the UK are diagnosed with GDM.

‘Women suffer a double shock’