DELHI, INDIA—Harinakshi Himati, an 18-inch, 10-pound baby born less than one minute ago to Delhi taxi driver Ganaresh Himati and his wife Chameli, has been declared the world's youngest person by the United Nations Census Bureau. "This is an honor, to be sure," said Mr. Himati, displaying his daughter to the public for the first time. "Her mother and I knew she was young, but this is very unexpected." Harinaksi displaced her older triplet Chaya as the world's youngest person and is expected to hold the title for a few seconds until the birth of her sister Varija.