This week, the governor of Georgia signed one of the most restrictive abortion laws in the country. It effectively outlaws the procedure after six weeks of pregnancy. Republican governors in three other states — Mississippi, Kentucky and Ohio — have signed similar laws this year, marking a new and more severe tactic by the anti-abortion movement.

The current constitutional standard under the Supreme Court’s Roe v. Wade decision is that abortion is legal up until the point when the fetus could survive outside a woman’s womb — usually about 24 weeks into the pregnancy.

What would these laws do?

These so-called “heartbeat” laws ban abortion after the point when a fetal heartbeat can be detected. This often occurs as early as six weeks into a pregnancy, when an ultrasound may be able to detect the pulsing of what will become the fetus’s heart.

These laws therefore move the ban on abortion in those states more than four months earlier than the current constitutional standard.