 All patients who require IVF treatment will be eligible for our study; even those who are already known for Glucose intolerance. Those patients being treated for this condition will not have their treatment affected in any way by our study, other than having one additional blood test on the day that they present for their down-regulation ultrasound. They will not be required to give a greater amount of blood, since vitamin D measurements can be determined from the same blood drawn routinely for estradiol E2 levels. 