Diabetes and obesity in pregnant mums Obesity in the mother is more common than GDM. While one in five women enter pregnancy obese, 4-6% develop Gestational Diabetes. As maternal obesity predisposes the baby to childhood obesity, optimising pre-pregnancy weight is recommended. Risk of childhood obesity Childhood obesity is associated with GDM. High sugar levels in the pregnant mother result in higher insulin hormone levels in the developing baby, which increases fat deposits.