The brown blotches that you are referring to is a condition known as melasma. Melasma is caused by groups of pigmented cells (called melanocytes) collecting in the skin of the face, especially on the cheeks and forehead just as you describe. The exact cause of melasma is unknown, but it is definitely worsened by pregnancy and also by some medications, especially birth control pills and medicines for epilepsy.
There is no easy cure for melasma. The condition certainly gets better after pregnancy, and even a year out (as in your case) it may continue to improve. Very strict skin protection from the sun is essential; this means both wearing sunscreen at all times whenever you go outside and also wearing a hat with a brim whenever you will be exposed to direct sunlight.
For anything other than these basic measures, you will need help from your dermatologist
. There are numerous bleaching creams, such as hydroquinone and azelaic acid, which can be of significant help. Similarly, chemical peels, when they are skillfully performed by your doctor
, can be of help. Laser therapy is an emerging technology which some doctors
You should begin by setting up an appointment with your dermatologist to discuss your options.