Marine Biology- Pregnancy effect on Dolphins

A recent study found that pregnant female dolphins have to adopt a whole new kind of swimming style to accommodate. The fetus in the womb of the mother causes the swimming to become much slower and the drag experienced by the mother was much more during pregnancy, it doubled near delivery. They changed their gait as well, by faster and more pumps of the tail to make up for loss in mobility of the tail.

More: http://www.macroevolution.net/pregnant-dolphins.html#.T67cf8VaKSo