A report published this week by Downing Street's social exclusion unit stresses the importance of lessons on relationships, which ministers believe will be a better context for teaching children the mechanics of sex.
School inspectors, who already check the quality of sex education, have been given until the autumn of 2000 to make sure they are trained to assess sex and relationships education.
The Government is also expected to give a higher priority to the wider area of personal, social and health education in the national curriculum.
Its role should be more clearly defined and teaching standards must be monitored effectively during school inspections, according to a separate report from the national advisory group on personal, social and health education.
Preparing Young People for Adult Life calls on the Government's curriculum quango, the Qualifications and Curriculum Authority, to define the contribution each curriculum subject can make towards PSHE.
It recommends a code of practice be drawn up and targets set for the performance of individual schools, and that this should be reflected in the way OFSTED assesses PSHE.
Teenage Pregnancy, the report from the social exclusion unit launched by Prime Minister Tony Blair, reveals that, despite constant references to sex in the media, pupils, especially boys, are still reduced to nervous laughter when the subject comes up in class and parents are uncomfortable discussing it at home.
Teenage fathers will be "vigorously pursued" by the Child Support Agency as soon as they start earning - a threat which the Government hopes will encourage boys to take the subject more seriously.
The Government plans to halve the teenage pregnancy rate by 2010. Of the 90,000 teenagers who give birth each year, 7,700 are under 16 and 2,200 under 14.
Under the action plan outlined by the social exclusion unit teenage mothers will be given learning mentors - at a cost of pound;6 million - to keep them involved in education.
Primary schools must make sure pupils understand puberty and childbirth. Secondary schools must explain the nature of relationships and be precise about where contraception can be obtained.
Schools will be obliged to make provision for teenagers to return after childbirth.