i think it depends on circumstances.
i haven’t got a baby. but my sister gave her son her last name because they were split up when he was born and the dad never saw him, he doesnt deserve any credit for my nephew, and my nephew has now got his step-dads last name.
but my bf’s sister gave her son her bf’s last name, but they were together when he was born, but not anymore. but he still has a lot to do with the baby, see’s him everyday etc…and how hard he works and much he loves his son i think the dad deserves it…
if u think the dad "deserves" it , i think its nice to give the dad that cos it’s a very "manly" thing to pass the name on to your children. if u understand what i mean lol, i didnt explain that very well.
but basically its ur desicion, its not bad to give a baby ur name if u and the dad arent married, many people decide different things, no one should judge u for it.
much love xx