there have been things to say that mum walking and being active - the movement of your hips etc.. make babies relax and they enjoy the rocking etc... so move less, compared to if you sit down and bub might move to get you moving a bit. another thing I have heard is light - more specifically sun light, they can see the reddy hue through your skin and the reddness etc.. soothes them and same thing they just enjoy it, but then darkness makes them more alert (or atleast doesn't put them to sleep), and so they move more in darkness eg at night, which then follows through outside the womb and why majority of bubs appear nocternal.

another thing, is if you are busy during the week maybe you just don't notice the movement as much as when you are not busy on the weekend.

either way, if at any time you are concerned about bubs movements you should get checked out =)