In the fall of 2019, Middle Kids were recording when they folded a precious sound into a brand new track. Lead singer and songwriter Hannah Joy was a few months into her pregnancy with her first child, and she and Tim Fitz, her husband and bandmate, had an idea: they recorded her 20-week sonogram, and wove the gentle, rapid thump of their baby boy’s beating heart into the last 20 seconds of “Run With You,” an exuberant declaration of devotion.