Eight-and-a-half ounces. That’s roughly the weight of two sticks of butter, a roll of quarters, or the cell phone you may be using to read this story. It’s also how much Evelyn Eilers weighed when she was born 17 weeks early at University of Iowa Health Care in September 2023, making her the smallest surviving infant in the U.S., and one of three tied for third-smallest in the world, according to…