During pregnancy your body goes through many changes and adapts to cope with the physical strain of pregnancy. Stretch marks are one example of this. Stretch Marks are series of lesions across the skin, usually found on the stomach and legs. Where the skin is under stress and pressure, it has to stretch to accommodate. Generally, your genetics determine to an extent whether or not you’ll form stretch marks: stretch marks come in various colours from pink to brown and all sizes, big and small.