It's not yet known why some women develop gestational diabetes and others don't, but you're more at risk if you:have a family history of gestational diabetes(ie your mother, grandmother or sister had it); have previously given birth to a large baby weighing over 4.5kg(9lb); are overweight or obese; have polycystic ovary syndrome(PCOS).Women whose families originate from certain areas are also at a higher risk. These include women from South Asia(specifically India, Pakistan or Bangladesh), the Middle East and black Caribbean women.
Attribution: BUPA