Women who are obese while pregnant have triple the risk of having a baby who develops type 2 diabetes later in life, research says.
The study of almost 120,000 women found pregnant woman who are overweight face a 40 per cent greater risk.
However, for expectant mothers who were obese while they were carrying their child, the risk was 3.5 times higher.
Scientists believe high blood sugar levels while the baby is in the womb may 'programme' them to develop the condition.
The researchers warn the findings are concerning, given one in two women of childbearing age in the UK tips the scales.
Women who are obese while pregnant have triple the risk of having a baby who develops type two diabetes later in life, research has found.
The data for the Edinburgh University study covered more than 60 years, in which time the level of obese mothers increased five-fold.
Lead researcher Professor Rebecca Reynolds said the study 'showed a significant association' between maternal BMI and children having diabetes.
Strategies to reduce obesity and overweight in women of childbearing age are urgently required, the team wrote in Diabetologia.
Professor Reynolds and colleagues analysed birth records of 118,201 children from 1950 to 2011.
These were compared to data from the national Scottish Care Information (SCI) - a diabetes register that covers every diagnosis in the entire population.
The reason for why a high BMI may lead to diabetes in unknown, and more studies are needed to explain the relationship, researchers said.
One theory is obesity in the mother produces an environment in the womb that is bad for the unborn baby's health.
This includes high levels of glucose, insulin and other chemicals leading to a 'programming' of adverse metabolic outcomes for the child.
In addition, there are complex hormonal, metabolic and inflammatory changes linked to obesity in pregnancy.
Type 2 diabetes is a condition which causes a person's blood sugar to get too high.
More than 4million people in the UK are thought to have some form of diabetes.
Type 2 diabetes is associated with being overweight and you may be more likely to get it if it's in the family.
The condition means the body does not react properly to
