Teenagers should learn how to bath a baby and change a nappy, a teachers' union has heard.
Many people have never changed a nappy before becoming a parent
Issues of discipline for toddlers and teenagers should also be covered, the national conference of the Professional Association of Teachers was told.
Lynn Edwards, outgoing national chair of the association, called for compulsory parenting classes for 14 to 16-year-olds.
She said many people became parents with little understanding.
"When I came out of the maternity hospital with a little boy on one arm and a little girl on the other, I had no idea how to put on a nappy," Mrs Edwards, a teacher from Birmingham, said.
"I found it unacceptable that no one had shown me."
Mrs Edwards said she was lucky because her mother lived nearby.
"Few people now are that fortunate - the extended family no longer occupies a village or urban neighbourhood."
As a result, few young people learned how to be "good parents on a practical basis" by watching other family members interacting with their offspring.
She said parenting classes should be taught in schools before children could legally become parents.
"It would need to cover the practicalities of caring for a child.
"It would need to give ideas and guidance on how to teach manners, road safety, the handling of money and what constitutes acceptable behaviour to young children within the family setting."
Feelings of parents
A spokesman for the Department for Education and Skills said: "The government assists voluntary and community sector bodies, through a variety of grant programmes, to support to parents, carers and families where it is needed.
"This includes work in schools and information advice and guidance on adult relationships and parenting.
"In the curriculum - within the personal, social and health education framework - pupils are taught at primary school about relationships in marriage and those between friends and families, and the skills needed for their development.
"At secondary school pupils learn about the role and feelings of parents and carers and the value of family life and good parenting."
The PAT annual conference takes place in Oxford this week.