By Hira Humayun, Michael Rios and Mounira Elsamra, CNN

(CNN) — The Dominican Republic deported dozens of pregnant women, mothers who had just given birth, and children, back to crisis-ridden Haiti as it cracks down on illegal immigration.

In a statement, Dominican authorities said the 135 women and children were taken to a detention center for undocumented migrants on Monday before being sent back to neighboring Haiti.

The sweeping deportations come as one of Dominican President Luis Abinader’s controversial immigration measures took effect, requiring staff at National Health Service (SNS) hospitals to ask patients for identification, a letter of employment and proof of residence, for immigration agents at the hospitals to verify.

On Monday, 33 public hospitals braced for the new policy. SNS Director Mario Lama said those hospitals are where up to 80% of public hospital births involving foreign mothers take place.

Dominican authorities say the women and children were detained because of the new protocol. They claimed in a press release that the deportees were treated humanely and with dignity, sent back on comfortable, safe buses only after they were discharged from the hospital and had a medical examination to make sure they were “free of health risks.”

Rights and health groups have criticized the move, with the UN on Thursday expressing concern that other women and children in the Dominican Republic may now fear health authorities. “We are very much worried about the potential impact on health,” Stéphane Dujarric, spokesperson for the United Nations Secretary General, said on Thursday.

The measure could have a “very quick and negative impact on those seeking healthcare who may not want to seek healthcare because they don’t feel hospitals are safe,” he said.

Although every country has the right to police its borders, it is also necessary for countries to “respect the dignity of other human beings,” Dujarric added.

The Dominican Medical Association said on Instagram such rigid deportation rules for people with medical needs could put their lives at risk.

The Dominican government has stressed that noone would be denied medical care under the new protocol – but rights groups say patients in need of care may steer clear of hospitals in fear of deportation.

“These individuals face immediate deportation after receiving care. This puts people’s right to health, privacy, and physical safety at risk—and discourages vulnerable groups, such as pregnant women, children, and survivors of violence, from seeking essential medical treatment,” Amnesty International said on Monday.

‘Approaching the point of no return’

Over the past six months Dominican authorities have deported more than 180,000 people back to Haiti, a country plagued by gang violence that has seeped into every aspect of life.

The Dominican Republic, which shares the Island of Hispaniola with its neighbor, has seen an influx of migrants fleeing violence in Haiti – where essential supplies are not keeping up with the population’s needs and hundreds of schools have shut down.

Dozens of health facilities have shut down in Haiti because of the insecurity, one of the latest being the University Hospital of Mirebalais. Late last month, gangs stormed the town, setting fire to buildings and posing a risk to the hospital, forcing it to evacuate its staff and patients, according to Partners in Health, the group supporting the hospital.

The United Nations’ top Haiti envoy María Isabel Salvador warned this week that Haiti is “approaching the point of no return.” She added: “Without timely and decisive international support, the violence will continue to escalate, and Haiti could face total collapse.”