What name does a baby take if the parents are not married?

What Last Name Does a Baby Get If the Parents Aren’t Married?

When a baby is born to unmarried parents, one of the first questions often revolves around the child’s last name. The answer isn’t always straightforward, but it largely depends on whether the parents take a specific legal step: signing an Acknowledgment of Paternity (AOP).

If both parents agree on the child’s last name—whether it’s the mother’s, the father’s, or a hyphenated combination—they can choose it at the hospital, provided they sign the AOP. This simple form officially recognizes the father’s legal relationship to the child and allows his name to be included on the birth certificate. Without it, the situation changes.

Without a signed AOP, the default rule in most states is that the baby takes the mother’s last name. In those cases, the father’s name typically won’t appear on the birth certificate, even if he’s present at the hospital or intends to be involved. This doesn’t mean the father has no rights, but it does mean legal steps will be needed later to establish paternity and, if desired, change the child’s name.

Signing the AOP at the hospital is often the easiest way to secure both the father’s rights and the family’s choice in naming. It can help prevent complications down the road—like issues with health insurance, inheritance, or school enrollment. It also gives the child the benefit of having both parents legally recognized from the start.

Ultimately, naming a baby is a personal decision. But for unmarried couples, it’s also a legal one. A quick conversation and a signature at the hospital can go a long way in shaping the child’s future—both legally and emotionally.