Waistbands, inseams and what each style of shorts is for
Shorts split into a few clearly different groups, and the waistband is what separates them. Denim and woven shorts usually rely on an over-bump panel or an elastic side insert, because the fabric itself does not stretch. Knit and lounge shorts use a soft roll-over or foldover waist instead, which is easier to adjust through the day. Fitted biker and cycling shorts are cut from stretch jersey throughout and sit high, with the panel built into the body of the garment.
Inseam length is the second decision and the one most often overlooked. A short inseam reads as summer or sport; a mid-length inseam is closer to a walking short and stays put more reliably under a bump. Brands publish the inseam in their own size charts, so it is worth comparing that figure rather than the style name, which varies between labels.
Fabric decides where you can wear them. Denim and cotton twill hold a shape and pair with a fitted top; jersey and rib knits are softer but show more. Stretch performance fabrics used in biker shorts are opaque when tested but can vary between colors, which is a detail each brand describes for its own product. Sizing is normally your pre-pregnancy size, with the bump room built into the pattern.