Almost half of the babies born in the UK are starting their lives in rented accommodation, according to a housing report from an insurance firm.
The Royal London says it is the first time in almost six decades a child is as likely to be born into a rented home, rather than owner-occupied.
Families with children privately renting have risen by 94% in a decade.
Becky O'Connor of Royal London says renting is "increasingly impossible to escape from" for young families.
The analysis shows how the so-called "generation rent" is becoming "generation parent", with 49.2% of children born to families who are renting, according to figures for 2016-17.
'Fraught' and insecure
About 365,000 children were born that year into rented homes, in a study drawing on the government's UK family resources survey and the English Housing Survey.
"For people in their late 20s and 30s, half of whom are starting families in insecure accommodation, not having a home of their own is fraught with practical and emotional issues," says Ms O'Connor, a personal finance specialist for the insurance company.
For about 200,000 families with children in private rentals, she says "the main risk is eviction, which hangs threateningly in the background of normal family life".
The report shows that from the 1960s, there was a steady increase in home ownership - and that by 2003-04, only about a third of children were born to families living either in private rents, council homes or in housing association accommodation.
The growth of owner-occupation, says the study, "seemed unstoppable".
But this post-war trend has gone into reverse - with a 94% increase in the number of families with dependent children living in privately-rented accommodation between 2006-07 and 2016-17.
Rite of passage
The report, the Parent Rent Trap, says: "Renting a home was once regarded as a rite of passage for the young... before 'settling down' to have children."
Because of "rising house prices and rising rents, young people are buying their first home later in life. Later, more often than not, than the age at which they have their first child".
Across the UK, numbers of renting families with children almost doubled in a decade to 1.8 million, with particularly big regional growths in north-east England, Yorkshire and the Humber and Northern Ireland.
Rented accommodation is becoming a long-term situation for young people, rather than temporary, and they are increasingly likely to be begin families while still renting.
The study shows that the average age for a first-time buyer is now 34, compared with 26 in 1997.
Figures for England, from the English Housing Survey, show how many people are renting later into adult life.
Among 35 to 44-year-olds, the proportion renting privately rose from 13% in 2007-08 to 28% in 2017-18.
"Too little policy attention has been paid to the position of families with children trapped for the long-term in potentially insecure private rented accommodation," the study concludes.