More children are born to foreign-origin women than native women in the UK, and over a quarter of all babies in England and Wales are born to mothers of foreign descent.
Data released by the Office of National Statistics (ONS) reveal that the immigrant group to have had the highest number of babies in 2011 was Polish who contributed to the highest number of non-British births with about 20,495 deliveries.
The UK had recorded 724,000 births in England and Wales in 2011, out of which 185,000 were born to non-native mothers.
There has been a 22% rise in the number of births per year since 2001. During the same time, the proportion of non-UK born mothers had steadily increased from 16% to 26%.
Among the EU countries, Romanian women had the highest fertility rate with an average of 2.93 children.
Non-EU women gave birth to about 130,000 babies the same year, out of which 18,434 were born to Pakistani mothers while about 14,892 had Indian mothers.
At the same time, the total fertility rates (TFR) of African countries surpassed the rest of the world.
Libya topped the list with about 5.58 births per woman, while Guinea and Algeria follow closely.
The ONS notes that the average fertility of Polish and Romanian women in their own country is much lower at about 1 child per women, but when they arrive in Britain, their fertility rates increase to about 2 to 3 births per woman.
The agency attributes the surge in fertility rates of foreign women in Britain to a broad range of state-funded benefits including better schools and living conditions.
With the easing of restrictions on labour market this January, the immigration and population trends are expected to continue.
However, the fertility of UK-born women also increased by 18%, from 1.56 births to 1.84 births, in the past decade, which could be ascribed to more advanced fertility treatments allowing people to start families later.
The highest percentage increase in fertility rates for native women was in the age groups of 40-45 and 35–39, with increases of 66% and 53% respectively, according to Mothers 35 Plus.
The population in England and Wales grew by over 3.7 million since 2001 and about two-thirds of the increase can be attributed to immigration and high birth rates among migrant mothers.