Boys are almost twice as likely as girls to be falling behind in their language skills by the time they start school, putting their chances of being successful in life at risk, according to a report from the charity Save the Children.
The study finds that in the past academic year alone, around 80,000 boys in England were behind in language and communication when they started school – equivalent to four boys in every Reception class. They often struggled to follow simple instructions or to speak a full sentence, it adds.
Unless action is taken to ensure all children have access to good quality early years education, almost a million more young boys could be left behind in the next 10 years, the report warns.
"The gender gap is well-documented," it says. "It has hardly changed for five-year-olds over the past decade, despite a dramatic improvement in overall results.
"The difference in outcomes for boys and girls is having a devastating impact; nearly a million boys have fallen behind with their early language skills since 2006.
"That is nearly a million five-year-olds who may struggle with skills like explaining what they think and how they feel, and engaging with the adults and children around them."
Lagging behind at the start of their school career is often an indicator that these children will continue to be behind later on, Save the Children said.
Overall, one in four boys were behind in language at the age of 5 in 2014-15, compared with 14 per cent of their female classmates. Poor white boys performed the worst, with around 38 per cent falling below the expected standard.
The study, which draws on official data and analysis of the Millennium Cohort Study, calculates that those who are not reaching the expected level at age 5 are four times more likely to be lagging behind in reading by the end of primary school.
Poor language skills prevent young children from being able to express themselves and engage with the world around them, and can affect their earnings, literacy skills and mental health as adults, it finds.
The report goes on to say that girls are outperforming boys in every area of the country, with the biggest gender gap in St Helens, Merseyside, where boys start primary school 17.3 percentage points behind their female classmates in language and communication.
At the other end of the scale, in Richmond, south-west London, the gap is 5.4 percentage points.
Call for early years investment
The report calls for the government to help develop a well-qualified workforce, with an early years teacher in every nursery.
"We cannot wait for disadvantaged children and boys to get to school before they receive the support they need," it says. "By this time many will have already fallen behind, with negative consequences for their childhoods, school attainment and life chances.
"We must invest in the best early years provision, led by early years teachers and supported by skilled staff at all levels, particularly in the most deprived areas."
Gareth Jenkins, director of UK poverty policy, advocacy and campaigns at Save the Children, said: "Every child deserves the best start in life. But in England, too many children, especially boys, are slipping under the radar without the support they need to reach their potential.
"They're falling behind before they even get to school and that puts their life chances at risk. In 2016, this is unacceptable. A whole generation of boys is being failed."
Andy Bowden, St Helens Council's cabinet member for education, said: "We're very aware of the gender issue, but it's important to point out that the data used in this report is up to two years old [from 2014-15].
"Since then, great efforts have been made to encourage nurseries to narrow the very evident gaps in children's development when they start nursery or school.
"We're also doing all we can to encourage parents and carers to help prepare their children for school with initiatives like Read and Rhyme Time in our network of local libraries."
A Department for Education spokeswoman said: "We are making a significant investment in the early years sector and the number of qualified staff is rising with more trained graduates in the workforce and a record number of providers rated "good" or "outstanding".
"This investment is paying off. [The] latest figures show more than 80 per cent of children are reaching the expected communication and language skills by age five, but we will continue working with the sector until every child gets the high-quality education they deserve."