According to David Paton, professor of industrial economics at Nottingham University, unwanted pregnancies have proved "remarkably resilient to policy initiatives", adding the under 16 pregnancy rate in England and Wales has remained virtually static for 40 years.
He said that between 1969 and 2009 the rate has risen and fallen, but not in time with national efforts to bring it down, the 'Telegraph' reported.
Family planning groups strongly dispute his findings, arguing that the evidence actually shows initiatives do work if given time.
They say drops since 2009 mean the rate is now the lowest since the end of the 60s.
"Millions of pounds have been spent by policymakers on numerous initiatives aimed at cutting teenage pregnancy rates," Paton wrote in the journal Education and Health.
"However, identifying the impact of policy interventions