A baby born weighing less than nine ounces and believed to be the smallest baby ever to survive has celebrated her first birthday.

Rumaisa Rahman, who weighed just 8.6 ounces at birth and was less than 10 inches long, turned a year old on Monday. She now weighs 13 pounds and is 24 inches tall.

Loyola University Medical Center, the suburban Chicago hospital where the girl received treatment until she was discharged in February, hosted a birthday party for Rumaisa and her fraternal twin sister, Hiba.

Hiba, who was discharged from the hospital a month before Rumaisa, was only 1 pound, 4 ounces at birth. She now weighs 17 pounds and is 26 inches tall.

Full-term, 1-year-old babies usually weigh around 20 pounds.

Doctors who cared for Rumaisa and Hiba said both are doing well.

"I feel very optimistic that I don't think that either of them will have any significant handicaps," said Dr. Jonathan Muraskas.

The girls' father, Mohammed Abdul Rahman, said doctors have told him the twins could be on the small side as adults but that only time would tell.

"If you have faith in God, everything is going to be OK," he said.

In June, Rumaisa was entered into the Guinness World Book of Records as the lightest birth in the world.

Madeline Mann, who was also born at Loyola, was the previous record holder. She weighed 9.9 ounces when she was born in 1989. She is now a high school honor student in the Chicago area.

Rumaisa and Hiba were delivered by Caesarean section (search) 14 weeks early at just 26 weeks' gestation after their mother, Mahajabeen Shaik, developed pre-eclampsia (search), involving dangerously high blood pressure.

Rahman and Shaik, who live in Hanover Park, are originally from Hyderabad, India. Rumaisa and Hiba are their first children.