definitely be honest. they'll probably ask why you left employment etc for that time anyway.
plus I have found the mums i've worked weith are much more efficient at their jobs. they know they have a limited number of hours to do what they are getting paid to do ie they can't stay back and do overtime cos they slacked off during the day or had a longer lunch. So they really get into it the minute they walk in the door. They are reliable and responsible - i'd say that's pretty good hiring characteristics!