Weed, insect, and disease control may also be required for pastures. A healthy, productive pasture will resist invasion from most poisonous weeds and provide good quality forage. When pastures are overgrazed, horses will eat the grass and legume species down to the soil, which allows weeds to take over.
1 Melasma can be triggered by birth control pills because it increases hormones throughout the body. # 2  This is one of the most common causes of melasma. 3  Pregnancy: During pregnancy the body will become very hormonal and skin conditions like acne vulgaris and melasma/chloasma become very common.
From the research I've done, it seems that some birth control pills cause melasma and the only way to (attempt to) prevent it is to use sunscreen. I use sunscreen every day (SPF 30) and have used an age spot/dark spots facial cream for the past 6 months.