Teenagers from Southwark have London's highest pregnancy rates
London boroughs have some of the highest teenage pregnancy rates in the country - with one in 13 young girls falling pregnant in some areas.
In Southwark, Lambeth, Lewisham and Haringey more than 70 out of every thousand girls aged between 15 and 17 are becoming pregnant.
That compares with a national rate of 41 out of every thousand, a report by the London Assembly highlighted.
Report author James Cleverly said more must be done to reverse the trend.
The figures show a huge variation in teenage pregnancy rates across the capital.
Girls in Southwark, the borough with the highest rates, are five times more likely to conceive than teenagers from Richmond.
The committee's report blamed insufficient sex education and a lack of leadership for the situation.
They recommended that sex education be a core component of school curriculums and suggested appointing a "sexual health champion".
Mr Cleverly, chairman of the London Assembly health and public services committee, said: "Young Londoners' sexual health is a major public health issue for the capital.
"Teenage pregnancies can have serious consequences for young people's health and life chances, as well as placing strain on NHS resources."
He added: "Our investigation shows that young Londoners' sexual health remains worryingly poor. More must be done."
The report also found the number of London teenager's catching sexually transmitted diseases has increased above the national average.
Lisa Power, corporate head of policy at sexual health charity Terrence Higgins Trust, said many young people in London were "clueless" about sexual health and how to avoid unwanted pregnancy.
"Providing quality sex and relationships education in London's schools is one of the most sensible steps we can take towards improving young people's sexual health," she said.
"It's also crucial that services are designed to be young people friendly and geared up to meet their needs."