The conception rate for women aged 40 and over has reached a "record high", according to official figures.
The Office for National Statistics (ONS) also said that teenage conceptions have fallen.
The latest figures show that the overall conception rate rose by nearly 3% between 2005 and 2006 from 76 to 78 conceptions per 1,000 women aged 15-44.
The conception rate in England and Wales rose between 2005 and 2006 for all women aged 19 and over.
The rate for women aged 40 and over increased fastest, by more than 6% from 11.5 per 1,000 women aged 40-44 in 2005, to 12.2 in 2006.
During the same period, the under-18 rate fell from 41.4 to 40.7 conceptions per 1,000 girls aged 15-17.
Although the UK's teenage pregnancy rate is the highest in Western Europe, in recent years there has been a gentle fall. The under-age conception rate also went down.
In 2006 it was 7.7 conceptions per 1,000 girls aged 13-15 compared with 7.8 in 2005, a decrease of 1%.
There were an estimated 866,800 conceptions in England and Wales in 2006, compared with 841,800 in 2005. The ONS said that as in previous years, nearly four-fifths of all conceptions resulted in a birth or births.
Since 1995, conceptions outside marriage have increased from 47% to 56% in 2006. The ONS said that much of this increase was in conceptions where both the maternity and conception were outside marriage but the birth was registered by both parents.
