"Gravity changes" refers to the concept that the force pulling objects towards the Earth's center can vary in strength or direction at different locations on Earth or in space. Full definition
You will notice your center of gravity changes as your pregnancy progresses because the weight you gain is not evenly distributed. (primamedgroup.com)
The team even placed the plants within a rotating plate to study how gravity changes root growth, which could one day help scientists understand the best ways to grow plants in space. (sciencemag.org)