Aims And Objectives : To study the risk factors predisposing women to gestational diabetes mellitus. STUDY DESIGN-A case-control study with 300 cases and 300 controls was conducted for a period of I I months (August 2007 -June 2008) in Sree Avittom Thirunal Hospital, Thiruvananthapuram, India. Materials And Methods : Universal screening was applied on antenatal patients with glucose challenge test (50 gm of glucose). If >130 mgl/o, subjected to oral glucose tolerance test(OGTT with 100 gin of glucose).NDDG criteria was taken to assign patients to study group. Information regarding characteristics and risk factors was recorded from patients on their admission for blood sugar control.