Phlebotomy

Every effort was made to perform phlebotomy fasting and performed before 10 am during the early follicular phase (EFP, between days 2 and 5) of a spontaneous menstrual cycle (prior to postmenopause). If an EFP sample could not be obtained after 2 attempts, a random fasting sample was taken within a 90-day window of the anniversary of the baseline visit. Collected specimens were initially stored between –20°C and –80°C at individual study sites for up to 30 days; they were then shipped to a central lab (either Medical Research Lab [Highland Heights, Kentucky, USA] or CLASS Laboratory at the University of Michigan [Ann Arbor, Michigan, USA]). Once at the central lab, samples were stored at –80°C.