Baby and the Beast by Victoria Sue

Desperate, pregnant, and alone, Nash is running out of time.

Hunted by his own father—the brutal Den Alpha who would slaughter his baby to keep their bloodline “pure”—Nash risks everything to find the elusive Shifter Rescue Pack before the winter storms seal off the mountains for good.
Nash realizes he’s finally run out of time when he goes into labor, and stumbles into an empty cave just as the snowstorm hits.
Casimir has turned his back on humanity and retreated to the mountains, and while shutting his hunter’s cave for the approaching winter discovers a young pregnant male who promptly collapses in Casimir’s arms. Realizing to his horror Nash is in labor, Casimir has no choice but to become involved with the shifter world he hoped never to have contact with again, only to discover tracker wolves are hunting them both, and closing in fast.
As a deadly snowstorm rolls in and hunters close in fast, Casimir knows time is running out. He must get Nash and the baby to Shifter Rescue—no matter the cost. But the deeper they trek into the frozen wild, the harder it becomes to ignore the bond growing between them… and the way Nash makes his long-dead heart beat again.

But then he also knows that the only way of keeping them safe is to leave them there.
Not after the blood on his hands.
Not after the past he can’t outrun.

Because some monsters don’t deserve a second chance.