Abby and Erin Delaney, conjoined twins who were born with a just 2% chance of life, recently achieved a remarkable milestone: they both completed kindergarten.

They were born on July 24, 2016, 30 weeks early, and from the beginning, they had an extremely complicated medical issue.

Their mother realized at 11 weeks of pregnancy that her daughters were craniopagus, connected at the skull. The twins were particularly susceptible to major difficulties because of this uncommon syndrome.

The girls had the same skin, skull, and “superior sagittal sinus,” a critical blood artery that drains blood from the brain. At the Children’s Hospital of Philadelphia, they had an 11-hour separation procedure on June 6, 2017. The surgery was successful despite the numerous risks involved. After the procedure, Abby and Erin spent five months in the hospital recovering.

Their successful kindergarten graduation today, despite making less progress than their colleagues, is a tribute to their parents’ and their own bravery.

When the parents, Heather and Ryley Delaney, found out early in the pregnancy that their twins were linked at the head, they were extremely astonished.

As Heather remembers, “It was a huge shock.” We never thought this would come to pass.

Doctors estimated their chances of survival at birth to be around 2%. When they learned that a rare surgical treatment would provide a chance for separation, hope was raised.

The twins, who weighed roughly 2.7 kg at birth, were admitted to neonatal intensive care right away before undergoing surgery in June 2017.

They recuperated in the hospital for several months following a rigorous 11-hour surgery.

While Abby is just starting to learn to walk, Erin has been walking since the age of five. Both daughters are enrolled in modified programs at a regular school and are improving daily.

They recently graduated from kindergarten, something that many people believed was impossible.

Abby was given a “Deer Award” for her generosity, and Erin was given a “Dolphin Award” for her “adventurous heart.” “The sky is their limit,” says their mother, Heather.