The cups are too small Now think of your bra cup. It is meant to contain your breast. If your breast is spilling out over the top or the sides, it's going to be pulling forward and down on the straps.2016-04-20
Why does my bra keep riding up?
The reason this happens is because the weight of the breasts is pulling down on the cups and straps and lifting the back upwards. The band may not be the correct size or the straps might be too tight. The bra band riding up is a sign that your bra does not fit properly.
Why does my bra lift up when I raise my arms?
If the bra moves up when you raise your arm, the band is too loose and you need to readjust the band. ... If yes, you need to increase cup size or change bra style that has side support and full coverage.
Why does my bra keeps coming up?
Measure your band size. The most common reason for ride-up is that the band is too big. You can avoid ride-up by getting a bra with a snug band. ... If your bra is riding up in front rather than in back, you may need a bigger band size.