Your employer can indicate you worked from Jan 2004 to Jan 2007 during which time you took a 6 month Maternity Leave (xxxx-xxxx dates). That way you are absolutely honest and if CIO wants to read it as a full 4 years, that's great, but you have spelled out your leave accurately. What do you think?
Thanks Pippin, that seems perfect, that way I can be honest and avoid doubts in the mind of the visa officer.