One in seven (14%) parents in the South West say that short-term rentals, which result in frequent and stressful house moves, have stopped their children feeling settled, according to a study by Shelter.
In the past decade, the number of families renting homes has more than doubled but the law has failed to keep up.
Renters only have a secure home for six months after which the landlord can ask them to leave with just two months' notice.
This instability means parents are concerned about the impact of constantly moving on their children, with 38% worrying they will have to change schools as a result of a future move.
Research shows that 42% of parents said searching for a new rented home had a negative impact on their personal life and 13% said a short-term rental negatively affected relationships with friends or family members.
Graeme Brown, Shelter's interim chief executive, said: "Soaring house prices mean more families are renting than ever before. But the dire state of our rental market means they can only secure a home for six months - the equivalent to just two school terms."
"Now is the time to fix this by introducing five-year tenancies across the board, allowing families to plan and save for the future and to feel secure and settled in their homes."