Teenage pregnancy in parts of England has fallen by almost half following the introduction of a government scheme.
Labour introduced Teenage Pregnancy Strategy (TPS) in 1999 and appears to have been a major success, research suggests.
Rates of teenage conception fell by half in some areas, while the greatest impact was seen in areas of high deprivation and those locations that receive the most TPS funding.
England's under-18 pregnancy conception is now at its lowest "since the 1970s", according to the scheme's lead researcher.
The strategy included providing high-quality sex and relationships education, youth-friendly contraceptive services, support for young parents, and co-ordinated action, at national and local level.
Grants to help implement the TPS were allocated according to teenage pregnancy rates in different regions.
The latest findings show that after peaking in 1998 the under-18 conception rate declined at a moderate pace until 2006, when it began to fall more sharply.
Between 1998 and 2013, it dropped from around 65 conceptions per 1,000 girls aged 15 to 17 to 34 in areas receiving the highest TPS funding.
Professor Adam Balen, from the Royal College of Obstetricians and Gynaecologists (RCOG), said sex education was likely to have been an important factor behind the trend.