The information requested falls within the responsibility of the UK Statistics Authority. I have asked the authority to reply.
Letter from Karen Dunnell, dated 7 July 2008:
As National Statistician, I have been asked to reply to your Parliamentary Question asking how many mothers are in employment. (215787)
Estimates are provided from the Labour Force Survey (LFS) household datasets. In the period April-June 2007, there were 4.8 million women with dependent children in employment.
The figure has not been adjusted for women with unknown economic activity status. It includes biological mothers, step-mothers and adoptive mothers with dependent children that live in the same household as them. Dependent children are children aged under 16 and those aged 16 to 18 who have never married and are in full-time education. Foster mothers, women with non-dependent children, and those whose children live in a separate household are not included.
There are currently no annual household datasets available. The figure given is or the April-June quarter, to be consistent with statistics published in the ‘Work and worklessness among household First Release’ (see web link:
http://www.statistics.gov.uk/pdfdir/work0807.pdf)
The household datasets are weighted to the population estimates published by ONS in February and March 2003. They do not incorporate the more recent population estimates used in the main quarterly LFS microdatasets.
The LFS is a sample survey covering over 52,000 households in the United Kingdom in each three month period. As with any sample survey, estimates from the Labour Force Survey are subject to a margin of uncertainty.