Weight gain between pregnancies increases gestational diabetes risk

A Norwegian study has found that the risk of developing gestational diabetes increases dramatically with weight gain between pregnancies.

Gestational Diabetes Mellitus weight pregnancy pregnant

New research from the University of Bergen in Norway has revealed that increasing Body Mass Index (BMI) above one unit from first to second pregnancy increases the risk of gestational diabetes mellitus (GDM), irrespective of a woman being overweight or not. GDM is defined as glucose intolerance of various degrees that is first detected during pregnancy, and is said to affect five to ten percent of Ireland's pregnant population. Both pre-pregnant body mass index (BMI) and gestational weight gain are known risk factors for GDM. The diabetes may cause a faster growth of the baby, and can cause health problems for both mothers and babies, during birth due to the size of the baby. Linn Marie Sørbye, of the university's department of global public health, says the condition is on the increase:

"We have little knowledge of the underlying mechanisms behind GDM, but we know that the disease has increased over time."

Sørbye and her colleagues used data from Norway's birth registry, including 24,198 mothers who had a first and second pregnancy between 2006 and 2014. The data included BMI at the start of each pregnancy as well as any diagnosis of GDM. The team say the results were surprising:

"Women who were overweight at first pregnancy had the highest risk of GDM. However, the strongest risk associated with weight gain between pregnancies was found in women with BMI less than 25 in first pregnancy. Surprisingly, we found a preventive effect of GDM in overweight women who reduced their BMI more than two units from first to second pregnancy."

The team believe that this finding should be added to pregnancy guidelines as a risk factor:

"Antenatal guidelines for monitoring GDM in pregnancy should add inter-pregnancy weight change as an independent risk factor for GDM with a routine stress-test of glucose tolerance during pregnancy in women with weight gain more than one BMI unit."