Cincinnati Zoo's famous hippo resident Fiona is going to be a big sister!After dropping multiple hints on social media about a baby on the way, the zoo confirmed Fiona's mother, Bibi, is pregnant. The baby is expected to arrive in the summer. “The hippo team is excited and also nervous,” Eric Byrd, manager of Cincinnati Zoo’s Africa team, said in a statement. “As most people know, Bibi’s first baby, Fiona, was born six weeks premature and wouldn’t have survived without the intervention of her human caregivers. We are hoping for a full-term pregnancy and will be doing everything we can to support Bibi.” Reproductive physiologists at the Zoo’s Center for Conservation and Research of Endangered Wildlife are working with the hippo team and have started Bibi on hormone supplements. They will also perform regular ultrasounds to monitor the growth and health of the fetus, zoo officials said. Eighteen-year-old male hippo Tucker arrived in Hippo Cove on Sept. 6, 2021, and was enamored with 23-year-old Bibi right away, zoo officials said. The pair had a breeding recommendation from the Association of Zoos and Aquariums Species Survival Plan Program, the group responsible for managing the health and genetic diversity in the hippo population in North American zoos. “We weren’t planning to welcome a baby this soon, but nature found a way and ignored our calendar,” Cincinnati Zoo’s director of animal care, Christina Gorsuch said in a statement. “Most forms of contraception, in hippos or humans, is not 100% reliable. The dose that was previously effective for Bibi did not prevent pregnancy this time.”Fans had been speculating on Bibi's pregnancy in the comments of the posts hinting at her pregnancy. Born six weeks premature at the Cincinnati Zoo on Jan. 24, 2017, Fiona weighed only 29 pounds at birth — 25 pounds less than the lowest recorded birth weight for her species. She survived because of her animal care team's tireless efforts to save her and has inspired many to care about her species and wildlife.