MMP9 and atrial fibrillation: AF was obtained during cesarean delivery, and the levels of intra-amniotic inflammatory mediators such as interleukin (IL)-1β, IL-2, IL-6, IL-8, IL-10, matrix metalloproteinase (MMP)-2, MMP-8, MMP-9, and tumor necrosis factor (TNF)-α were measured using a Human Magnetic Luminex assay (R&D Systems, Minneapolis, MN).