Every now and again, my mother will look at my sisters and me with a self-satisfied little smile and declare, “I grew you girls!” Technically, she’s correct. She successfully performed one of nature’s coolest party tricks and produced three other healthy human lives. Furthermore, she suffered no birth-related injuries or residual complications (except for the mild mental derangement that most parents develop). Mom has every right to feel proud of her achievements. But the odds for such happy outcomes were stacked in her favor.