The attempted execution went ahead after the US Supreme Court overturned a reprieve granted by a lower court on Wednesday morning.

Justice Brett Kavanaugh, a conservative, granted the application to vacate the stay of the execution. No explanation was provided in the order.

The top court’s three liberal justices – Sonia Sotomayor, Elena Kagan and Ketanji Brown Jackson – dissented.

Sotomayor wrote that the decision cleared the way for Tennessee to execute Pike before her pending legal challenges to her conviction “can be properly considered”.

“Tennessee’s desire to expedite Pike’s execution by a few days or even weeks cannot outweigh her ‘fundamental interest in [her] own life,” she said.

The state’s order for the execution at Riverbend Maximum Security Institution in Nashville was due to expire at midnight.

After the attempted execution, Dr Joel Zivot, a professor at the Emory University School of Medicine, said Pike likely never achieved a sufficient blood level of pentobarbital to cause apnoea and cardiovascular failure.

“It’s very possible that as a consequence of the delay of the beginning of resuscitation she will have a brain injury,” Zivot, an expert on physician participation in lethal injection, said.

In a ruling earlier on Wednesday, judges from the US Court of Appeals for the Sixth Circuit paused the execution saying they needed more time to consider the arguments in Pike’s case.

Pike’s lawyers said that for years, the state of Tennessee had argued in court that she lied about being sexually abused as a child.

But at a recent hearing about her execution method, the state said it did not dispute that she had suffered sexual abuse and rape.

Pike’s legal team asked the appeals court to send her motion back to the district court, arguing that if the federal courts had based their ruling on the state’s earlier claim that she was lying, then the federal review was affected.

It was the second time in as many days that the US Supreme Court gave the go-ahead for the convicted murderer’s death by lethal injection. On Tuesday, the justices rejected a different appeal from Pike.

Tennessee’s governor also denied a clemency request this week from the death row inmate.

At the time of her incarceration, the 21-year-old was the youngest person on death row, according to the Tennessee Department of Corrections.

Pike is the only woman currently serving a sentence on Tennessee’s death row.

Since 1976, when the Supreme Court resumed the death penalty, only 18 women have been executed in the US, compared to 1,663 men. That’s about 1% of all US executions.