Heterosexual Britons in their 30s and 40s are half as likely as teenagers to use a condom when having sex with a new partner for the first time, the United Kingdom’s Daily Telegraph reports.

A study published in the International Journal of Epidemiology showed that nearly 70 percent of people between the ages of 16 and 19 used a condom with a new partner compared with 38 percent of men and 29 percent of women between ages 35 and 44.

“Our finding that condom use at first sex declined with increasing age is of concern,” said study co-author Catherine Mercer, PhD, a lecturer at the Centre for Sexual Health & HIV Research at University College London. “Increasing rates of STIs diagnosed among those in their 30s and 40s suggest that interventions that promote consistent condom use with new partners are urgently required.”

According to the article, of the 11,161 study participants, 9,598 reported a total of 15,488 heterosexual partnerships in the last year. Men reported that they had sex sooner after first meeting a partner than women, with one in five reporting sex within 24 hours of meeting his or her partner compared with one in 10 women.