Parents would no longer be able to withdraw their children from sex education classes once they turn 15, The Times of London reported. Currently, the opt outs are available until age 19.
The new rules would take effect in 2011 if they are approved.
"Sex and relationship education is a very important element and we see it as crucial to our drive to reduce teenage pregnancy," Schools Secretary Ed Balls said.
At age 5, students would learn about parts of the body and get some education on relationships.
Schools operated by religious groups would be allowed to offer sex education "within the ethos of their faith." But they would be required to provide accurate factual information.
"You can teach the promotion of marriage, you can teach that you shouldn't have sex outside of marriage -- what you can't do is deny young people information about contraception outside of marriage," Balls said.