Around a third of children in England are falling behind in their development by the time they start primary school, government figures show.
Pupils from poorer backgrounds were also far more likely to be below a good standard in their learning, literacy and numeracy levels.
More than 200,000 youngsters are behind when they first start school, a failing Save The Children said was "shocking" and denied children "a fair start in life".
The Department for Education figures for 2016 showed that 31% of early years children - those up to the age of five - are not achieving a good level of development in areas such as communication and language, maths and social skills.
Boys are behind girls, with 62% achieving good levels compared with 77%.
But the disparity between those from more disadvantaged backgrounds was the most glaring, with 54% of children eligible for free school meals reaching a good level of development compared with 72% of all other children.
Just 654 people started teacher training for early years-age children this year, which Save The Children said was far short of the number needed to address the 11,000 shortfall.
Kevin Watkins, the charity's chief executive, said: "It's shocking that in this day and age so many children in England, particularly the poorest, are at greater risk of falling behind by the time they reach school because of our chronic shortage of nursery teachers - a shortage that shows little signs of improving.
"Every year, hundreds of thousands of children without access to these teachers are starting reception struggling to speak full sentences, follow basic instructions, and learn subjects like maths and sciences.
"But the consequences won't end there. We know that children who start behind are more likely to stay behind throughout their lives, with huge implications for the rest of their schooling, their jobs, and even their future relationships.
"This isn't right - we are robbing children of opportunity and denying them a fair start in life. Every child - no matter what their background - deserves the chance to reach their full potential.
"If the UK government is truly serious about creating a country that works for everyone, it must give all children the support they need by investing in an early years teacher in every nursery across the country."
The Liberal Democrats accused the Government of "sneaking" the statistics out while the focus is on the Autumn Statement.
Leader Tim Farron said: "The Government have their priorities on education all wrong and are failing the least well off. While they pour £240 million into divisive grammar schools for a select few they are leaving hundreds of thousands of children behind.
"This Government should be spending cash on things like the Pupil Premium which would help every child achieve their potential."
A Department for Education spokesman said: "We are clear that high quality early education is vital in giving all children the best chance to fulfil their potential.
"These results show a continued rise in the number of children reaching the expected standards, with the gap between disadvantaged children and their peers also decreasing
"We are determined to go further to improve quality, which is why we are doing more than ever to help attract and retain the best staff and are investing a record £6 billion per year in childcare by 2020."
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