The number of girls undergoing female genital mutilation has fallen dramatically in east Africa over the past two decades, according to a study published in BMJ Global Health.

The study, which looked at rates of FGM among girls aged 14 and under, suggests that prevalence in east Africa has dropped from 71.4% in 1995, to 8% in 2016.

The reported falls in the rates of FGM are far greater than previous studies have suggested, though some in the development community have advised caution over the figures.

In February, the United Nations Population Fund warned the number of women predicted to be mutilated each year could rise to 4.6 million by 2030, an increase driven by population growth in communities that carry out the practice.

According to the study in the BMJ, the rates of FGM practised on children have fallen in north Africa, from 57.7% in 1990 to 14.1% in 2015. In west Africa, prevalence is also reported to have decreased from 73.6% in 1996 to 25.4% in 2017.

The study aimed to assess if FGM awareness campaigns targeted at mothers had been successful. Unlike many other studies, older teenagers and adult women – who tend to have higher rates of FGM – were not included. The research developed estimates by pooling and comparing FGM data by proportion across countries and regions, using a meta-analysis technique.

Nafissatou Diop, coordinator of UNFPA-Unicef joint programme, said it was possible that girls included in the study would still undergo FGM at a later point in their teenage years.

“Some girls who have not undergone FGM may not have reached the customary age for cutting and may still be at risk,” said Diop. “The age at which the girls are undergoing FGM changes from ethnic group to ethnic group. In Kenya, for example, the Somali community practice FGM on girls aged three to seven. But in the Maasai community they practice FGM when the girl is a teenager, aged between 12 and 14.”

Although global FGM rates are falling, she added, increasing numbers of girls will be living in countries where FGM remains prevalent by 2030.

“Because of the demographic trends, the absolute number of girls and women undergoing FGM will continue to increase,” said Diop.

UN analysis suggests that rates of FGM among girls aged 15-19 have fallen from 46% in 2000 to 35% in 2015, according to statistics across 30 countries with nationally representative data.

The authors also warn that while rates of FGM are falling in many areas, this downwards trend could easily be reversed.

“If we think, ‘OK, let’s celebrate,’ and we don’t continue with the same efforts, that may have reverse consequences,” said Ngianga-Bakwin Kandala, the report author and professor of biostatistics at Northumbria University. Risk factors – such as poverty, poor quality education and support for FGM among some religious leaders – continued to persist, he said.

The study was based on data collected through demographic health surveys, developed by ICF International, and multiple indicator cluster surveys, which are directed by Unicef. Data ranged from the years 1990 to 2017 for 29 countries across Africa, and two countries in western Asia: Iraq and Yemen.

Kandala added that trends varied both within and between countries.

Across Yemen and Iraq, FGM prevalence increased by 19.2% per year between 1997 and 2015, though rates remained lower than elsewhere.

The report drew on 90 sets of survey data, covering 208,195 girls.

The report did not examine the reasons why FGM rates had fallen, but said it was likely to have been driven by policy changes, national and international investment. National laws banning FGM have been introduced in 22 out of 28 practising African countries, according to the campaign group 28 Too Many.

In Somalia, where there is no national legislation expressly criminalising FGM, anti-FGM campaigner Ifrah Ahmed said the practice was still prevalent. “I remember being at a school in Mogadishu asking girls about FGM. All the girls said they were already cut. Just one said she hasn’t yet,” she said, adding the girls were aged between seven and 12 years old.

“Nothing will change until you change the religious leaders’ [attitudes] because they are very powerful in the community,” added Ahmed, founder of the Ifrah Foundation, which supports women and girls who have undergone FGM, and girls who are at risk.

The report concluded that if the goal of eliminating FGM was to be reached, further efforts were urgently needed, including working with religious and community leaders, youth and health workers.

“This package of comprehensive intervention could include legislation, advocacy, education and multimedia communication,” the report said.