Over 800 healthcare professionals have outlined their opposition to new abortion laws due to come into effect in Northern Ireland next month.
Abortion is to be decriminalised in the province from October 22 unless the Stormont Executive meets before that time.
The changes to the law, which are being made after MPs in Westminster passed legislation in the Commons earlier this year, will make abortion possible up to the point of viability.
Hundreds of doctors, nurses and midwives have signed the letter to Julian Smith, Secretary of State for Northern Ireland, saying that their "consciences demand that we not be silent".
The letter, also addressed to Northern Ireland health secretary Richard Pengelley, appeals to the UK Government "not to impose this unwanted legislation".
It also asks that Northern Ireland's elected representatives "re-establish a functional Northern Ireland government so that democratic process be restored".
"The concept of taking a human life at any stage is inimical to us, and the concept of taking a human life in the womb especially so," they write.
They add: "We appeal to the wider society to consider and reflect on the humanity and value of every life, from conception to death, that the weakest and most vulnerable would be protected and cherished by all."
Dr Andrew Cupples has sent the letter to Stella Creasy, the Labour MP who tabled the motion in Parliament that led to the changes.
He told the Belfast Telegraph he feared for the right to conscientious objection.
"We have a lot of Christians who very strongly feel that the unborn child is a human being with value and worth. On the same side we have a strong compassion and a real desire to care for woman in crisis pregnancies," he said.
"At the moment Northern Ireland has the best and most protected care for women and unborn children. On October 22 it will have the worst in western Europe. The unborn child in the womb will have no legal rights up to 28 weeks."