Idaho has become the second state this week to enact a so-called 'fetal heartbeat' law banning abortions after just six weeks - before many women know they are pregnant. 

Republican Governor Brad Little on Tuesday signed into law the legislation that would outlaw nearly all abortions in the state by banning them once a fetal heartbeat can be detected. 

Gov. Little signed the bill that contains a 'trigger provision,' meaning it won't go into effect unless a federal appeals court somewhere in the country upholds similar legislation from another state. 

The move comes a day after Oklahoma signed a bill banning abortions after a fetal heartbeat is detected.

This week governors in Arizona and Montana also signed anti-abortion laws and last month protesters gathered in Arkansas to demonstrate against a new ban on nearly all abortions in the state. 

Gov. Little's bill makes providing an abortion to a woman whose embryo has detectable cardiac activity punishable by up to five years in prison. It would also allow the woman who receives the abortion to sue the provider.

Fetal cardiac activity can be detected as early as six weeks using an invasive vaginal ultrasound — before many women discover they are pregnant.