Challenges in recruiting and retaining experienced practitioners are forcing nurseries to turn to staff without the skills and knowledge to effectively support children, Ofsted is warning.
The inspectorate's report into the early years sector found that this is leading to a drop in the quality of support for children, particularly around personal, social and emotional development.
This is because "those with greater experience and a higher level of qualifications had better knowledge of child development" and were more likely to interact with children during their day, talk with them about their emotions and activities they are involved in, found Ofsted.
"Conversely, less skilled practitioners often distracted children instead of helping them understand and manage their emotions," states the report.
"For example, when children were upset about returning indoors, we saw practitioners using distraction techniques instead of explaining rules and expectations, indicating a lack of understanding of children's thinking and emotional needs."
A third of workers surveyed by the inspectorate say "they were thinking about leaving the early years workforce and finding a different kind of job".
Recruiting to replace them, settings are having to hire more apprentices and staff "less qualified than the practitioners they had hired previously".
Ofsted also found "unhelpful misconceptions" among some early years staff about babies and toddlers.
One in 25 believe that "babies and toddlers are too young to be taught anything", despite evidence to the contrary.
Among nursery managers surveyed one told the inspectorate that "working in the baby room is seen by the uninitiated as mere babysitting, but on starting the role, new recruits realise that there is a huge amount of responsibility involved".
Ofsted's report points out a drop-in support for younger children is "especially important now" as from September this year expansion of free hours for working families "mean there are likely to be more babies and toddlers in early education and care".
The inspectorate's deputy director of early years regulator policy and practice Jayne Coward added: "We know that a child's first few years are crucial to their future learning and development.
"By providing children with an excellent start in those first two years, we can ensure that they gain the foundation they need to thrive throughout school and beyond.