More than 550 Northern Ireland women have had NHS abortions in England since the service became free last year.
That's a 14% rise in terminations in the last eight months, according to figures collated since charges were abolished by the government last June.
The revelation comes at a time when MPs and peers from many parties - including the Conservatives, who govern with the support of the DUP which opposes abortion - are signing up to support its legislation here.
In a letter to Home Secretary Amber Rudd, over 130 parliamentarians have urged the Government to bring in legislation to allow equal access to abortion so that Northern Irish women can get abortions locally rather than having to go to England.
It follows a UN declaration that forcing women to travel for an abortion is an infringement of their human rights, and campaigners believe the law could be changed in a forthcoming domestic violence bill.
Data provided by Marie Stopes clinics reveal they conducted 363 terminations for Northern Irish women in England between June 30, 2017 and February 28 this year, while the British Pregnancy Advisory Service carried out 190.
In 2016, 724 local women had abortions in England, according to the Department of Health, which is equivalent to 483 over an eight-month period.
Stella Creasy, the Labour MP who led the campaign to drop the fee for abortions, is now spearheading moves to legalise NHS abortions in Northern Ireland.
She said the scale and cross-party support for the change should force the Government's hand.
"We have heard talk of the importance of regulatory alignment between Northern Ireland and the rest of the UK but that concern does not seem to extend to the basic human right of not to be forced to continue an unwanted pregnancy," she told the Guardian.
"The UN ruling is clear that forcing women to travel to seek an abortion is not acceptable. It's time for all who say they support gender equality to put their votes and their voices where their marching is and back this call for progress."
Northern Ireland's abortion laws are stricter than the rest of the UK.
Terminations are only permitted if a woman's life is at risk or there is a serious or permanent risk to her mental health.
Rape, incest and fatal foetal abnormalities are not circumstances in which an abortion can be performed legally.
The Irish Cabinet yesterday - International Women's Day - gave the go-ahead to have a referendum on the liberalisation of Ireland's abortion laws. The move comes after a Supreme Court ruling in Dublin on Wednesday that protections for the unborn child offered under the state's constitution do not extend beyond the right to life.