Overuse of baby equipment and electronic screens can impede the physical and emotional development of under-threes, a charity has warned.
What About The Children? (Watch?) says modern lifestyles could be harming infant brains.
It highlights strapping small children into pushchairs, and the increased use of smartphones and tablets as being particularly damaging.
It says these could have an impact in later life.
Watch? promotes the importance of secure attachment in the early years and the vital role that loving care plays in brain development.
It is holding a conference in London today focused on how the first three years of life shape a child's emotional, physical and mental health "forever".
'Eye contact, singing and talking'
It will highlight the importance of the physical interaction and social engagement between small children and "consistent, loving carers".
The charity says it is particularly concerned about the impact of modern lifestyles on the brain development of babies and toddlers.
Sally Goddard Blythe, director of the Institute for Neuro-Physiological Psychology, is speaking at the conference.
"Social interaction helps physical development, for example eye contact, singing and talking. That is not happening if a child is in a forward-facing buggy and her mum is using her smartphone," she said.
"Infants need opportunity for free movement and exploration whether that is tummy time, cuddling or rough play.
"Attention, balance and co-ordination skills learned during the first 36 months of life support cognitive learning and have been linked to school performance later."
Another contributor, June O'Sullivan, from the London Early Years Foundation, stresses the importance of relationships.
"Children's wellbeing starts with positive attachment to adults who are attuned and responsive," she said.
"If they understand the children's emotions and put their fears into words, it is very reassuring to the child.
"Wellbeing in the early years is the foundation of success at school, in making friends and relationships and for all adult life."