Our flanges are normally oriented with the tab side down, which has an angle that allows you to lean back without spilling milk.
Some people do use the flange upside down successfully, but that direction makes it hard to get the nipple in the flange deep enough, reducing stimulation and milk output, and often indicates that something else isn't right.
Certainly feel free to try it, but keep in mind that we're here to help if upside down isn't better.
Reviewed by Diana West, IBCLC
June 24, 2021