Does litter size determine gestation time?

I took Zoey to the vet abaout a week ago and from the x-ray they took they told me she would have at least 5-7 kittens. The past two nights she has had a little bit of a brownish discharge and today she has been meowing when I touch her belly. But my qeustion is, is gestation shorter with larger litters and shorter with smaller? Thanks for your help!

Its the same with all.