The stresses and strains of family life push 40% of parents with children under five to "breaking point", according to a survey.
Home-Start UK, a family support charity, found almost two thirds (63%) believe their stress can damage their relationship with their children.
Almost all (93%) of the 1201 parents quizzed by YouGov on behalf of the charity said their children's future mental and physical wellbeing could be affected.
Vivien Waterfield, Home-Start's Director for Fundraising and Communications, said: "Every year 35,000 families who feel they have nobody to turn to are turning to us for help as they face crises such as poverty and isolation.
"We support almost 73,000 vulnerable children across the UK and our services are being stretched. In some parts of the country we just cannot keep up with demand.
"We believe that there are an unacceptable number of families at breaking point and, without the funding we need, we are forced to turn away potential volunteers because we simply do not have the money to train them.
"And the inevitable consequence is that struggling families and vulnerable children are left without much needed support."