Anti-abortion campaigners are increasingly targeting students at UK universities, where there has been a rise in the number of anti-abortion societies on campus and demonstrations by outside groups displaying graphic imagery.

The campaign has gathered momentum on the back of a continuing debate about freedom of speech in universities. Some student unions have been threatened with legal action if they attempt to prevent anti-abortion groups opening on campus.

There have been reports that there are now at least 14 anti-abortion societies in university students’ unions around the UK, many of which have faced fierce opposition from students who are overwhelmingly pro-choice.

Most recently there have been a series of demonstrations by anti-abortion campaigners outside Cardiff University, which have prompted counter-protests by some students. The rise in tensions followed a vote by the students’ union to adopt an official pro-choice stance, in common with other universities.

Isadora Sinha, a postgraduate student of bioinformatics at Cardiff, proposed the motion which gained overwhelming support when put to a vote in November. Since then there have been at least three anti-abortion protests outside the university, organised by the Centre for Bio-Ethical Reform UK (CBR UK), which recently targeted the pro-choice Labour MP Stella Creasy.

There have been anti-abortion societies at Cardiff students’ union before, but in October a new anti-abortion society opened called Cardiff Students for Life. Its website encourages members to get involved with the wider anti-abortion movement through events such as the annual March for Life and “40 days of life” vigils outside clinics.

Sinha said she and other pro-choice activists had received online threats from external parties following the vote and had been in virtual hiding for two weeks. “The motion was written in a way to ensure free speech and expression for those who are pro-life and the pro-life society can function as before. Unfortunately, there has been backlash against this motion passing despite it having passed by a democratic vote by hundreds of students.”

Students’ unions at universities including Birmingham, Nottingham, Aberdeen and Strathclyde have been forced to lift bans against anti-abortion groups when faced with possible legal challenges over free speech.

An organisation called the Alliance of Pro-Life Students (APS) supports students to set up their own anti-abortion societies. It encourages them to affiliate with their students’ unions in order to gain access to facilities, resources, students’ union funding and training opportunities.

The APS chief executive, Madeline Page, said there were 14 affiliated societies in the UK, with at least two in the process of affiliation. “Our societies remain autonomous and students are welcome to run their society as they see as most appropriate to their university’s setting,” she said. “We do not dictate how they should be run, nor do we run any societies as an organisation.”

Where legal heft is required, a faith-based legal advocacy group called the Alliance Defending Freedom, or ADF International, intervenes to remind universities of their responsibilities to protect freedom of speech, an issue which both the government and the higher education regulator have recently addressed.

Dr Pam Lowe, a senior lecturer in sociology and policy at Aston University, researches anti-abortion activism across the UK. “The anti-abortion movement has collectively recognised they have got an ageing population. They are setting out strategically to try to engage more younger people and get younger people advocating against abortion.

“This is a deliberate policy, that’s quite new. It’s an orchestrated campaign, but where exactly it originates is unclear to me,” she said. “There’s no sign that it’s really being successful at the moment.”

Rachel Watters, the NUS women’s officer, said the union did not hold data on societies of this kind but agreed the anti-abortion movement was more visible on campuses, but it did not reflect any change of heart among students. “Students’ unions and students have been passionate in campaigning about reproductive rights issues for decades.”

She suggested that recent changes to the law on abortion in Northern Ireland had brought the issue back into focus. “I don’t think the general opinion of students will be massively influenced by the growth of these societies. Anti-choice societies have the right to express their views. Of course, students’ unions, people in the student movement, also have a right to challenge what they are saying.”

Kerry Abel, who chairs the campaigning group Abortion Rights, agreed: “Anti-choice campaigners on campus are not new, but their strategies are – they are becoming more brazen. It’s not acceptable for students’ access to healthcare and information to be blocked or interfered with.”

The CBR UK chief executive, Andy Stephenson, said anti-abortion activities were being being targeted at students “as universities are attended with people very likely to have an abortion”. He said the demonstrations in Cardiff would continue for the foreseeable future, with protests planned once or even twice a week for the new year. “The only thing that would make us stop such frequent displays would be the students’ union reversing its advocacy for abortion and mistreatment of pro-life students.”

Nicola Dandridge, the chief executive of the Office for Students (OfS), England’s university regulator, said institutions had a duty to provide inclusive and safe environments, and to consider the needs of all students.

“Universities are places where people can encounter challenging and – at times – uncomfortable ideas, and see those ideas questioned, sometimes for the first time. This is something which we should encourage, and the OfS stands for the widest possible definition of free speech. But that challenge must take place in a respectful environment in which civil discourse can thrive.”

Additional reporting by Shanna Jones

• This article was amended on 7 January 2020 to clarify in the text and subheading that the NUS was not the source of the data relating to the number of pro-choice student groups. The text was also changed to clarify that the OfS is the university regulator in England, not the whole of the UK.