Approximately 3-8% of pregnant women can develop gestational diabetes, often at around 24 to 28 weeks' gestation. Factors that can increase the risk of developing gestational diabetes include: being over 30 years of age; having gestational diabetes in a previous pregnancy; having polycystic ovary syndrome (PCOS); having had a baby in a previous pregnancy whose weight at birth was more than 4.5 kilograms; being overweight or obese; having a family history of type 2 diabetes or gestational diabetes, and; taking steroids or anti-psychotic medications. Women from some cultural and ethnic groups are also at a higher risk, including: Aboriginal and Torres Strait Islanders; people of Indian descent; people of Vietnamese and Chinese descent; people of Middle Eastern descent, and; people of Polynesian or Melanesian background.