Mandatory sex and relationship education for children as young as four is needed to reduce the rising teenage STI and abortion rate, according to two leading sexual health charities.
By Tulip Mazumdar
Newsbeat health reporter
Brook and Family Planning Association (FPA) claim the government is failing young people because they're not giving them enough information about the emotional side of sex and relationships.
Chief Executive of Brook Simon Blake says the government need to "make it part of the curriculum, signal to people that you (the government) really are serious and we will see some impact on teenage pregnancy, on abortion rates, on access to contraception".
The number of under 25s with the most common STIs, including chlamydia, genital warts and herpes, rose in the last set of statistics between 2005 and 2006.
The latest abortion figures showed a 10% rise in the number of under 16s having terminations.
Getting the facts right
Julie Bentley is chief executive of FPA. She said: "Young people will find information and if we don't give it to them in a responsible way, they'll find it from elsewhere. Pornography is a good example… what it does is it distorts their understanding about sex."
Children in Norfolk learn to differentiate body parts
But Sarah Jane Hayes, who has two children, aged six and one, said: "It's far too early. I wouldn't be discussing it with my children at that age so I wouldn't want the school to be doing it… because they're too young to understand and they don't need to know at that age."
Northern Ireland has just this year made Relationships and Sexuality Education compulsory for school children from the age of five, but critics say the delivery of the new curriculum has been "patchy".
Elsewhere, schools must teach pupils the basics of human reproduction as part of their science lessons, but there is nothing in there about the emotional side of sex and relationships.
Brook and FPA say those aspects are the most important when it comes to giving children the confidence in the future to make safe decisions about their sexual health.
'Not making it into a big deal'
Freethorpe Primary School in Norfolk has been teaching Sex and Relationship Education since 2005.
Year 2 pupils who are six and seven years old learn about the difference between male and females.
They use laminated cards with the names of body parts including, shoulder, kidneys, vagina, penis, and arms, to learn which parts belong to both sexes or just males or females.
Juliet Le-Grice co-ordinates their SRE programme.
Mum of two Kerry Johnson thinks four is too young
She said: "The focus is developing their self-esteem and knowledge so they can make informed healthy life-style decisions.
"With the knowledge that within Europe, Britain has a high pregnancy rate. It is important to give them those ideas from a very young age."
But outside the school gates 23 year-old mum of two Kerry Johnson says "doing it (sex and relationship education) from the age of four, means they're going to think about it more.
"When really, at four years-old they shouldn't be thinking about it at all. I think they should just be kids."
The government in England is looking into whether to make Sex and Relationship Education compulsory.
Ministers in Scotland and Wales say they have no plans to make it compulsory at the moment.