Ohio became the latest state in the US this year to ban abortions after 20 weeks, but vetoed the 'heartbeat bill' which prohibited abortion at around six weeks when fetal heartbeat becomes detectable.

Fifteen other states have 20-weeks ban on abortion, but the 'heartbeat bill' would have been the strictest abortion regulation in the country as most women are not aware of pregnancies before week six.

Governor John Kasich is known to have taken a pro-life stance in the abortion debate, but vetoed the 'heartbeat bill' because he said that odds of legal challenges were stacked high against the bill.

"The State of Ohio will be the losing party in that lawsuit and, as the losing party, the State of Ohio will be forced to pay hundreds of thousands of taxpayer dollars to cover the legal fees for the pro-choice activists' lawyers. Furthermore, such a defeat invites additional challenges to Ohio's strong legal protections for unborn life," he said in a statement.

Similar measures have faced legal challenges in other states, the news service goes on to say, a fact weighing heavily in Kasich's veto defense. Kasich noted bans in two other states had been declared unconstitutional.

The 'heartbeat bill' was considered by the Ohio Senate many times in previous years, but was never passed because of the unlikelihood of its withstanding legal challenges.

At least forty three states have some form of abortion restrictions tied to phases of fetal development and viability of the fetus outside the womb. Some states have restrictions linked to time after conception. In other states, the laws that make abortion illegal after viability of the fetus are not dependent on time period of pregnancy.

Abortion rights groups were against both the 20-week ban and the heartbeat bill. Some expressed plans to challenge the new 20-week ban.

“There’s no way we’re going to take this lying down,” Gabriel Mann, spokesman for Naral Pro-Choice Ohio, told the New York Times. “It’s too horrific of a restriction for women who are facing medical complications and situations where they need an abortion around that 20-week period.”

Some pro-life organizations welcomed governor's decision to pass the 20-weeks ban while vetoing the 'heartbeat bill.'

"While it must have been difficult, the current makeup of a radically pro-abortion Supreme Court required the governor to exercise great restraint," said Ohio Right to Life President Mike Gonidakis. "By endorsing the 20-week ban in lieu of the heartbeat approach, Gov. Kasich provided strong pro-life leadership to finally engage a winnable battle with the federal judiciary while saving countless babies at the same time."