Health professionals have raised development concerns about one in five toddlers.
Official research also reveals youngsters are far more likely to suffer stunted progress if they come from a deprived background.
In Tayside, 21% of children aged 27-30 months had a problem in at least one measure in a 2016/17 review that assessed categories such as speech and behaviour.This compared with 19% in Fife. The Scotland average is 18%.
Iain Gray, for Scottish Labour, said the figures, published by the Scottish Government on Tuesday, were “deeply worrying”.
“We already know that you are less likely to succeed in school if you come from a deprived area – and these figures suggest that deprivation impacts children during early years too,” the MSP said.
“The reality is the SNP has cut more than £1.5 billion from lifeline services since 2011, including from schools and early years.”
Toddlers in the most deprived areas of Scotland (24%) were much more likely than those in the least deprived to have a concern recorded.
Boys are almost twice as likely to have an issue as girls.
In Dundee, 22% of toddlers were falling short in at least one development measure.
Gregor Murray, the children and families convener at Dundee City Council, said: “The council and its partners from Angus and Perth and Kinross councils, along with NHS Tayside, are working together on the Tayside Plan for Children, Young People and Families, which looks at early years as one of its main priorities.
“This is a new way of trying to develop more joined up working across a set of priorities so that we can do the very best we can for our children and young people.”
NHS Tayside’s existing family strategy says achieving the milestones at 27-30 months is “crucial to ensuring readiness to learn on entry to school and provides a strong foundation for subsequent childhood development”.
The milestones most frequently missed in the area were in speech and language, emotional and social development, as well as attention.
Public Health Minister Aileen Campbell said: “Early support for young children with speech, language and communication helps to ensure better outcomes for these children.
“We recognise that the ability to communicate and connect with people is a vitally important life skill and is key in supporting educational attainment.”
At Holyrood, Labour MSP Anas Sarwar told under-fire Health Secretary Shona Robison she needed to “step up or step down” after he linked the “shameful” trebling of early retirements in NHS Tayside to her leadership.
Ms Robison said NHS staff numbers had “increased by 13,000 under this Government, with more doctors, nursing and midwifery staff delivering care for the people of Scotland”.