"To adopt a newborn" means to legally become the parent of a baby that is just born, typically by going through a process that allows you to provide love, care, and a home for the child as if they were your own. Full definition
We met at a local restaurant and she explained that she had just adopted a newborn baby boy and she was inducing lactation so she could breastfeed him. (mamasaywhat.com)
I'm a gay man who adopted a newborn last year. (gayparentmag.com)
At my age, my odds of adopting a newborn were slim, and I feared that a pregnancy might compromise my health. (health.com)