The color of your skin is determined by the melanin or pigment in the skin. Level of melanin depends on genetics and sunlight exposure. A number of people have pigmentation related to hormonal change and sunlight exposure. Skin pigmentation results from the body produce either too much or too little melanin which creates blotchy or uneven skin tone.
If the pigmentation already exists, there are a few ways to treat them:-
Skin care that contains Alpha Hydroxy Acids (AHAs) which helps to exfoliate the upper most layer of the skin.
Skin care that contains ingredients that inhibits the melanin production e.g. kojic aid, arbution (found in bearberry , mulberry, and cranberry extracts), vitamin A (Retinol) . Some of these ingredients are available under prescription cream only. It needs to be taken under precaution.
The best thing you can do to avoid the pigmentation is to wear a high SPF broad spectrum sunscreen everyday and reapply it regularly. You may also benefit from antioxidants especially for vitamin C and vitamin E which helps to fight against damaging effects of sun exposure.