OHIO (REUTERS) - The number of abortions in the United States continues to drop decade after decade, but demand for "abortion pills" is on the rise.

Data provided to Reuters by over a dozen clinics and Planned Parenthood sites shows that so-called "medication abortions" are becoming more common in places, such as Ohio, where, until recently, laws made it difficult to obtain the pills.

Reuters correspondent Jilian Mincer said: "What we're seeing is a dramatic shift in states like Ohio, Texas which until the spring limited how it could be used. Now it will be available further along in someone's pregnancy up until 10 weeks. And that's making a huge difference because before it was only up to 49 days gestation, so we're seeing rates triple in those locations."

Here's how a "medication abortion" works. It involves taking two pills within a 24- to 48-hour period. The first blocks the hormone progesterone.

The second induces uterine contractions. Studies show this method has a roughly 95 per cent success rate.

A change in FDA regulations this year means medical professionals other than doctors such as nurse practitioners and physicians' assistants can also prescribe the medicine.

The pills are most widely used now in Iowa clinics where they account for 64 per cent of all abortions according to Planned Parenthood.