The Society for the Protection of Unborn Children is challenging calls for more explicit sex education for primary school children.
At present, sex education is not compulsory for primary school children but the Government is currently consulting on whether to allow teachers to teach more explicity about puberty, parts of the body, and reproduction.
Under Government proposals, there are still some restrictions and pupils would not be taught "how reproduction occurs".
In a letter published in The Telegraph on 19 July, the Sex Education Forum, Lucy Faithfull Foundation, Mothers' Union, UK Faculty of Public Health and the Royal College of Nursing criticised the restrictions and said the essentials of sex education should feature "unambiguously" in the science curriculum.
They argued that more explicit sex education was necessary to protect children from the risk of abuse and misinformation caused by accessing explicit sexual images on the internet.
"Perhaps most worryingly, the [Government's] proposals undermine teaching children the correct names for genitalia," they said.
"This will perpetuate shame, and brings the risk of children not having the language to understand their bodies or to recognise and report sexual abuse.
"Children have a right to learn about human reproduction without feeling such subjects are taboo."
However, the Society for the Protection of Unborn Children questioned the safeguarding argument and warned that it could lead to children having an "unhealthy interest" in their sexual organs.
They added that including this teaching in science lessons, as opposed to sex education lessons, deprived parents of their legal right to withdraw their children.
In a letter of response published in The Telegraph on 22 July, SPUC said: "This supposed need for children aged five to seven to be able to name correctly their genitalia is not going to safeguard them.
"Quite the reverse, it will stimulate an unhealthy interest in their sexual organs and is a violation of their privacy. Most parents are not drawing their children's attention to genital organs and schools shouldn't either."