A pregnant Texas woman who was seeking court permission for an abortion in an unprecedented challenge to one of the most restrictive bans in the US could not wait any longer and went to another state, her lawyers said on Monday.

The announcement came as Kate Cox, 31, whose foetus has a fatal condition, was awaiting a ruling from the Texas Supreme Court over whether she could legally obtain an abortion.

Her baby’s diagnosis has low survival rates and her attorneys said continuing the pregnancy jeopardized both her health and ability to have more children.

Nancy Northup, president and chief executive of the Centre for Reproductive Rights, which was representing Ms Cox said: “Her health is on the line. She’s been in and out of the emergency room and she couldn’t wait any longer.”

The organisation did not disclose where Ms Cox went.

On Monday, she was 20 weeks and six days pregnant.

The court, which is made up of nine Republican justices, had given no timetable for a ruling.

On Friday night, the court had paused a lower a judge’s order that gave Cox permission for an abortion.

Ms Cox, a 31-year-old mother of two from Dallas, had been to the emergency room at least four times since becoming pregnant in August, according to her attorneys.

Ms Cox was believed to be the first woman in the US to ask a court for permission for an abortion since Roe v. Wade was overturned last year.

Her lawsuit quickly became a high-profile test of bans in Texas and a dozen other GOP-controlled states, where abortion is prohibited at nearly all stages of pregnancy.

Days after Ms Cox filed her lawsuit, a pregnant woman in Kentucky also asked a court to allow an abortion.

There has been no ruling yet in that case.

Earlier on Monday, two medical groups in the US urged the Texas Supreme Court to grant a final ruling in favour of Ms Cox.

Her lawyers said that she had been to the emergency at least four times since becoming pregnant again in August.

Texas’ abortion ban makes narrow exceptions when the life of the mother is in danger but not for foetal anomalies.

Republican Texas Attorney General Ken Paxton, who has defended the state’s strict anti-abortion laws for nearly a decade, argued that Ms Cox did not demonstrate that the pregnancy had put her life in danger.

“The Texas Legislature did not intend for courts to become revolving doors of permission slips to obtain abortions,” Mr Paxton’s office wrote in a filing to the state Supreme Court last week.

Dr Leilah Zahedi-Spung, a maternal fetal medicine specialist in Colorado and a fellow with Physicians for Reproductive Health, said when lethal fetal anomalies are diagnosed “there’s only risk to that pregnant person and no benefit unfortunately for that innocent child”.

“You are putting your body through risks without any benefit because prolonging the pregnancy doesn’t change the survival rate,” Dr Zahedi-Spung said.

Doctors told Ms Cox that her foetus has a condition known as trisomy 18, which has a very high likelihood of miscarriage or stillbirth and low survival rates, according to her lawsuit filed last week in Austin.

They also told Ms Cox that inducing labour or carrying the baby to term could jeopardise her ability to have another child.

Trisomy 18 occurs in approximately one in 2,500 diagnosed pregnancies, according to the American College of Obstetricians and Gynaecologists and the Society for Maternal-Foetal Medicine.

There is no live birth in about 70% of pregnancies involving the diagnosis that proceed past 12 weeks gestational age, according to a legal filing that the two groups submitted to the court.

The termination of pregnancies because of foetal anomalies or other often-fatal medical problems is seldom discussed in national debates over abortion.

There are no recent statistics on the frequency of terminations for foetal anomalies in the US but experts say it is a small percentage of total procedures.