Around one in three of babies born last year in Peterborough have mothers born in the EU, according to the Office of National Statistics (ONS).
Figures show that last year, 878 of the 3,072 births in the area were born to EU-born mothers, a rate of 28.6%.
This is one of the highest percentages of births to EU-born mothers across the whole of England and Wales.
In total, 47.5% of the babies had mothers born outside the UK - higher than the national average of 28.4%.
Of the estimated 1,459 non-UK-born mothers who gave birth last year in Peterborough, EU-born mothers made up 60.2%. Mothers from European countries outside the EU made up 2.8% of the group, 25.6% were from the Middle East and Asia, and 8.4% from Africa.
The ONS report said that the figures for non-UK born mothers includes those who moved to the UK as children and have lived there most of their lives, as well as those who have recently migrated.
It also said that the figures for UK-born mothers include the children of second or third generation immigrants.
Analysis of the Annual Population Survey by the Migration Observatory at the University of Oxford found that there is a higher proportion of migrants among people of childbearing age.
In 2017, 28% of 30 to 39-year-olds were not born in the UK - compared with 14% of the population overall.
Migration Observatory director Madeleine Sumpton said that this partly explains why the national numbers are high.
She said: “People migrate at all ages, but in general it’s harder for families to migrate.
“People in their 20s and early 30s generally have fewer attachments, and it’s more worthwhile for them to move.”
The Migration Observatory also reported that 62% of foreign-born residents have been in the country for more than 10 years, and that a third arrived in the UK when they were under 18.
Ms Sumpton said: “Migrants who arrived in the country as children are relatively settled, and in many cases they will be socioeconomically indistinguishable from the UK-born.”
The lowest percentage of births to EU-born mothers was in Redcar and Cleveland and South Staffordshire, where just 1.5% of mothers were originally from the EU.
ONS senior statistician Liz McLaren said: “There are large variations in the percentage of births to women born outside the UK across England and Wales.
“This is due to local area differences in the percentage of women born outside the UK, and due to differences in fertility levels of migrants born in different countries.”
In the five years from 2012 to 2017, the total number of births in Peterborough fell - from 3,270 births in 2012 to 3,072 last year.
During the same period, the number of births born to non-UK-born mothers increased - from 1,356 births in 2012 to 1,459 last year.