The shirt Alex Abend is wearing for the 2024 United Airlines NYC Half marathon on Sunday has an image of two tiny footprints on the front. The footprints are of her first child, James. He was stillborn on Jan. 11, 2022, when Abend was 34 weeks pregnant. It is an unfathomable tragedy that has driven Abend, an attorney from Montclair, to raise awareness about stillbirth, defined by the Centers for Disease Control as the death or loss of a baby before or during delivery. Abend is running her first half-marathon, 13.1 miles, as a fundraiser for PUSH for Empowered Pregnancy, a nonprofit organizatio…