Ohio last week became the seventh state to pass a bill that makes abortion illegal if a fetal heartbeat can be detected.

This bill, called a "heartbeat bill," has become increasingly popular among anti-abortion policymakers and is seen as a step toward overturning Roe V. Wade. Eleven states, including New York, have a version of this legislation pending.

Fetal heartbeats can be detected as early as six weeks, when many women do not yet know they are pregnant.

“These laws have been ruled unconstitutional because in Roe v. Wade, abortion was permitted up until viability, normally defined around 23 weeks of fetal development," medical ethicist Art Caplan said on Boston Public Radio Thursday. "After that, the fetus, in theory, can live outside the woman's body.”

Caplan is the Drs. William F and Virginia Connolly Mitty chair and director of the Division of Medical Ethics at NYU Langone Medical Center.