 Mothers will have their OGTT at 24-28 weeks gestation and further blood, urine and stool optional samples will be taken at this time for study purposes. Modified WHO 1998 and NICE criteria will be used to diagnose gestational diabetes or noti.e. fasting plasma glucose 6.1 mmoll OR fasting plasma glucose 6.1 mmoll and 2 hour plasma glucose 7.8mmoll but 11.1 mmoll on 75g glucose tolerance test. The criteria will be changed if the new IADPSG criteria is adopted during the course of the study or NICE updates its criteria. The mothers will be asked to fill out further psychological well-being questionnaires during the waiting time during the OGTT and for mothers subsequently diagnosed with GDM, when they attend the antenatal-diabetes clinic. 