Visa rejections have threatened progress on mother and baby health after experts from struggling countries were barred from talks, global midwife leaders have said.

Politicians, donors and UN agencies convened this week at the International Confederation of Midwives (ICM) congress in Lisbon, Portugal, a key conference to discuss the millions of avoidable mother and baby deaths every year.

But last-minute visa refusals meant eminent midwives from Africa and Asia – where the majority of lives are lost – were excluded.

Urgent appeals were lodged for delegates from countries including Nigeria, Ghana, Rwanda, Burundi, Uganda, Tunisia, Ethiopia, Sierra Leone, Bangladesh, India and Indonesia.

ICM advisor Kate Stringer said: “These midwives are leaders working in countries that bear the highest burden of deaths.

“A mother dies every two minutes due to pregnancy or birth. How are we going to intervene if the researchers and professors at the heart of it are banned?

“This defies logic. It is a life and death situation, perpetuated by colonial bias.”

In Uganda, midwife Harriet Akello runs a lifesaving initiative that has caught the attention of the World Health Organization (WHO). She was due to speak in Lisbon on how fragmented, high-risk maternity systems can reorient to a “midwifery model of care” – where a mother is kept safe by a small team of skilled midwives.

With her work at the NGO Mother Health International, Akello helps overwhelmed public maternity centres pivot to WHO standards, operating in a remote post-conflict region near the border with South Sudan, 95km (60 miles) from a referral hospital.

Akello said, “The world’s policymakers are in Lisbon, yet here I am in Uganda, trying to explain to an embassy why I should have the right to travel. I am gutted and insulted. The WHO says we need ‘midwifery models of care’. I have a rare example of this, but I’ve been silenced.”

Having recently travelled to Sweden for work, she added: “I was in a Schengen country in the past year. I didn’t overstay – I have too much to do for mothers in Uganda.”

Two Bangladeshi midwifery union leaders were denied visas despite a male government official flying to Lisbon to pledge 25,000 extra midwives for the country.

Similarly, Dr Arthur Munkana from the Democratic Republic of the Congo voiced frustration for four midwives who had to stay behind. “Our country is devastated by mothers dying. Good quality midwives are a key solution – yet only I got a visa.”

Stringer called this “gender inequity laid bare”.

Alison Perry, a researcher at Imperial College London, said a Ugandan midwife she collaborates with was also excluded. “This represents overt discrimination against equitable participation in international conferences,” she said.

Portugal’s Ministry of Foreign Affairs said visa assessments happened “rigorously, objectively and factually” in line with Schengen rules.

Globally, about 260,000 women die every year in childbirth, 1.9 million babies are stillborn and there are 2.3 million newborn deaths. About 70% of mothers die in sub-Saharan Africa, with much of the remainder in Asia.

The WHO has called on governments – including the UK – to make “midwifery models” a core service. The world is a million midwives short of safe staffing levels, according to the ICM.

This week, the ICM also covered childbirth bleeding, which affects 27 million women a year, kills 43,000 and costs countries more than £7bn. New data published in the Lancet found six critical factors for survival, including accurate, timely diagnosis and access to blood transfusions.