It comes as the government published the new national curriculum for all subjects, with the exception of English, mathematics and science, ahead of implementation in 2014.
Existing programmes of study have been disapplied as of this term to give schools “greater flexibility to manage the transition from the existing national curriculum to the new one”, the Department for Education said.
A consultation on the future of the national curriculum ended in April this year.
However, among the reaction this week organisations representing PSHE education said that teachers would be left confused by the changes to the subject because of missed opportunities to strengthen safeguarding.
FPA, a sexual health charity, said schools were being forced to teach sex and relationships education using guidance that was issued 13 years ago in 2000.
Natika Halil, the organisation’s director of health and wellbeing, said: “We live in a different world now, where young people can so easily be exposed to confusing and misleading sexual imagery and content on the internet and on mobiles and SmartPhones.
“Despite recent assurances from David Cameron that he would support sex and relationships education being ‘up-to-date on the problems of the internet’, there is nothing in the government’s new guidance to help teachers broach some of these very real and very modern issues.
“Guidance that is 13-years-old also fails to take into account more recent legislation, not least issues covered by the Equality Act.”
She added that there were vital elements missing that would give children a more rounded knowledge of issues that might affect them.
Meanwhile, the Sex Education Forum, said the new curriculum was confusing and would hinder teaching.
Chairwoman Jane Lees said: “While puberty is clearly included in science, teachers are discouraged from explaining how reproduction occurs and about hormones.
“Omitting sexual health from the curriculum fails to prepare children properly for adult life. The government has missed a perfect opportunity to link up their education policy with their stated commitment to improving the nation’s sexual health, just days after the prime minister talked about the need to modernise sex and relationships education to make sure it is relevant to the lives of children today.
“We urge both primary and secondary schools to consult pupils about their sex and relationships education to make sure that what they provide responds to their needs. Every child has a right to learn about their body and their health.”