i don't know that it would cause pregnancy to last longer, but moving a pregger could cause them to terminate the pregnancy. It could also cause birth defects. (but usually if there is a drastic change in parameters or she is VERY pregnant)
Pysgodyn.
When her gravid is pitch black, she'll be soon to birth. Also froma front view, her stomach will be VERY square. Pregnancies usually last 5-weeks (On average). When she shows these signs, and she doesn't give birth with in 24grs, raise the temp a few degrees 3, 4, or 5 o F I wouldn't go much higher than 83o f of 84 (18 C)