There were over 650 abortions in the six months leading up to October after laws were relaxed by Westminster, according to the Evangelical Alliance Northern Ireland.
Abortion was decriminalised on 22 October 2019, but the regulations did not come into effect until 31 March.
David Smyth, head of the Evangelical Alliance in Northern Ireland, said the first anniversary of decriminalisation was a "dark day" for the province.
"We grieve that since the end of March more than 600 women saw no better choice than abortion, and for the unborn lives lost," he said.
"In the bitter face of another wave of this pandemic, and with the extraordinary measures our government and society are putting in place to save lives, it seems all the more ironic that so many lives are simultaneously being lost through abortion – lives that are deemed unwanted, unchosen or unimaginable.
"We continue to stand with the vulnerable today in the midst of this pandemic, those who are disabled, in care, in crisis, lonely and marginalised.
"We continue to advocate for the dignity and welfare of both women and unborn children. We imagine and work for a better future because as Christians we believe in life after death, life before birth, and life in abundance, even in the mess of the here and now."
Abortion laws were relaxed in Northern Ireland despite widespread opposition in the province, with 79% of respondents to Westminster's public consultation opposing the changes.
Dawn McAvoy, co-founder of the Both Lives Matter campaign group, wrote in the Belfast Newsletter that the changes will lead to more pregnant women facing discrimination and coercion to choose abortion.
She also voiced regret over the "silence and inaction" of Church and civic leaders in the face of the changes.
"Both lives matter and abortion must not be normalised here as it has been elsewhere, nor must the denial of human rights for pre-born children, by abortion activists such as Amnesty International, be allowed to permeate our culture," she said.
"Government must be held to account and challenged to offer genuine choice," she added.
