Prevention of Gestational Diabetes Mellitus With Lifestyle Intervention Among Women of Advanced Maternal Age.

Inclusion Criteria: * local resident in Beijing * Singleton pregnancy * Aged ≥35 years * Overweight or obesity (Body mass index is between 24 and 27.9 kg/m2 or ≥28 kg/m2) * ≤12 weeks of gestation * written informed consent is obtained Exclusion Criteria: * Diagnosed with type 1 or type 2 diabetes before pregnancy * Diagnosed with GDM or impaired glucose tolerance at enrollment * use of medication that influences glucose metabolism currently, such as metformin, etc. * multiple pregnancy * current substance abuse * unable to exercise due to physical disability * diagnosed severe psychiatric disorder * Other conditions not suitable for intervention as judged by physicians