Dying 9-Year-Old Boy Bailey Cooper Hung On Just Long Enough To Meet His Baby Sister

Nine-year-old Bailey Cooper had just relapsed from cancer for the second time in 2017 when he learned that his mother, Rachel Cooper, was pregnant. Despite his dire prognosis, Bailey could only think of one thing: his future baby sister.

“All he was concerned about was meeting his little sister. Bailey knew something wasn’t right. He could feel it in himself,” Bailey’s dad, Lee Cooper, 31, tells PEOPLE. “We got told the news late August that he wasn’t going to survive. We were told it was days to weeks. We were very open with him. He was taking it in … He was thinking, ‘Oh no, I won’t meet my sister.’ ”

Just months earlier, Rachel and Lee, of Bristol, U.K., revealed to their sons, Bailey and Riley, now 7, that she was pregnant and later learned that they’d have a little sister, Millie. The news proved to be a pick-me-up for the ailing boy, who had been diagnosed with non-Hodgkins lymphoma in 2016.

“When we told him, it completely lifted him. He was completely over the moon,” Lee says, adding that Bailey was an extra special part of his mother’s pregnancy.

“He was amazing. He was adamant on being around Rachel,” Lee tells PEOPLE of Bailey. “He’d always be cuddling her, trying to listen to the baby in her tummy. He’d sing to her. He was just anticipating meeting her. He’d read stories while resting his head on her tummy. He’d sing just so the baby would be familiar with his voice.”

Bailey told his family that he’d try his hardest to live to see Millie’s birth. And he did. Millie was born on Nov. 30, 2017.

“He just managed to hang on, basically. How he did it, we don’t know,” Lee says of his son, adding that he was “smitten” by little Millie. “He’d come into the hospital, he sat down. He was getting quite frail, but he’d come straight in as quick as he could, shuffling his feet. We had to pass Millie to him. He just sat in the chair with Millie in his arms and he wouldn’t let her go.”