The number of teenage pregnancies in England and Wales has fallen to the lowest level since 1969 when records began.
Office for National Statistics data show the under-18 conception rate is now 24.5 per thousand women compared with 27.9 per thousand the year before.
This is a drop of 13%. Pregnancies in under-16s also fell.
At the same time, however, the conception rate among women over 35 has been rising.
Historically the UK has had one of the highest teenage pregnancy and abortion rates in Western Europe.
In recent years the government put a series of strategies in place in an attempt to get these figures down.
But the sexual health charity the FPA says there is no room for complacency.
Harry Walker, a spokesman for the charity, said: "We are no doubt still seeing the lasting effects of the government's 10-year teenage pregnancy strategy.
"But the danger with getting good news year on year is that people start to take their eye off the ball and forget that the figures we are seeing today are the result of a complex series of actions over a number of years by professionals at a national and local level.
"Any complacency now and we will see a knock-on effect in years to come."
The charity says the UK is still lagging behind other countries in Western Europe.
According to their records in 2012 the UK had lower teenage pregnancy rates than only Bulgaria, Romania and Slovakia of the 28 countries of the European Union.