Rumaisa (Roo-may-sa) Rahman, the smallest baby in the world, weighing 8.6 ounces (260 grams) – about the size of a cell phone. Rumaisa and her sister, Hiba, (Hee-bah) were born on Sept. 19, 2004, at Loyola University Medical Center at 25 weeks and six days of gestation by a caesarean section.