Each woman now has 1.91 children on average—the highest since 1973—according to the Office for National Statistics.
As a result the number of births—690,000—increased by 20,000 in 2007 compared to the previous year, when there were 1.86 children per woman.
One factor in the rise is the tendency for foreign-born mothers, particularly from the Indian sub-continent, to have large families.
Another is women choosing to have children when they are in their more fertile 20s, rather than delaying until they are in their 30s and 40s.
However, those who do delay are having more children due to improvements in fertility treatment.
The figures, which relate to England and Wales, indicate the overall fertility rate has now increased for six successive years.
Its lowest point came in 2001 when it sank to 1.63 children per woman.
However, last year’s rate is still far lower than in the 1960s when it reached a peak of 2.93 children per woman in 1964.
Lois Cook, the ONS statistician behind the provisional figures, said the analysis showed women across the country and of all ages were contributing to population growth.
Ms Cook said: “It is quite complicated and there is not a single explanation such as older mothers or migrant mothers.
“Apart from women under 20, all child bearing age groups are experiencing a rise in fertility rates which could mean fewer are putting off having a family and deciding to have children before they reach 30.
“It is true that rates are also going up among women in their 30s and 40s. But in the early part of 2001 there was evidence more women were delaying motherhood.”
The proportion of births to foreign-born women now stands at 23 per cent, an increase of 1 per cent.
On average, foreign women have 2.5 children each, rising to almost five for those from Pakistan, and 3.9 from Bangladesh.
The number of babies born to British mothers is also increasing, but lags far behind immigrants at an average of 1.7 children each.
Compared with 2006, there have been increases in fertility rates for all age groups except for women under 20. The highest percentage increase was observed for women aged 40 and over with an increase of 6 per cent compared with the previous year.
Fertility rates for women aged 40 and over have more than doubled in 15 years since 1992 and in 2007 reached 12.1 births per 1,000 women.
Last year 3,345 infant deaths were registered, giving a rate of 4.8 deaths per 1,000 live births. This is the lowest rate ever recorded in England and Wales.
The ONS has predicted the UK population could reach 71 million by 2031, with migrants and their UK-born children accounting for 69 per cent of that growth. Part of the reason for the explosion is Eastern European women, particularly Poles, having more children in Britain.
The number of deaths registered increased for the first time since 2003. In 2007, there were 504,052 deaths in England and Wales representing an increase of 0.3 per cent compared with 2006.
Circulatory diseases, such as heart disease, are still the most common major cause of death contributing to over one third (34 per cent).
Cancer accounted for just over a quarter (28 per cent) of all deaths registered in 2007, with a rate of 2,133 per million population for males and 1,545 for females. Since 1997 death rates for cancer have fallen, by 16 per cent for males and 12 per cent for females.