Melasma may be initiated by pregnancy and oral contraception, hence the popular term "mask of pregnancy". Women in whom melasma develop during pregnancy should not be treated until several months after delivery because the dark spots often fade spontaneously. However, avoidance of sun light exposure and daily use of a sunscreen during pregnancy may retard the development of melasma.

Patients taking birth control pills are generally instructed to stop taking them to increase the likelihood of successfully lightening the pigment with depigmenting agents. At present, no data exist to suggest that birth control pills containing low amounts of estrogen, or a progestogen only, are less likely to produce melasma; thus, changing to these drugs does not facilitate lightening of hyperpigmentation.

In general, melasma of recent onset respond better than long standing cases, & the melasma of epidermal type, as determined by Wood’s light respond faster than the mixed epidermo-dermal type.

What are the main Causes of Melasma?
Melasma has been considered to arise from pregnancy, oral contraceptives, endocrine dysfunction, genetic factors, medications, nutitional deficiency, hepatic dysfunction, and other factors. The majority of cases appear related to pregancy or oral contraceptives.

The infrequency of melasma in postmenopausal women on estrogen replacement suggests that estrogen alone is not the cause. In more recent experience, combination treatment using estrogen plus progestational agents is being used in postmenopausal women, and melasma is being observed in some of these older women who did not have melasma during their pregnancies.

Sun exposure would appear to be a stimulating factor in predisposed individuals. Although a few cases within families have been describe, melasma should not be considered a heritable disorder. Sunscreens & Malasma
Sunlight is one of the major factors that influences the increased functional state of melanocytes in melasma. Its high incidence in tropical areas, and the recurrence of the hyperpigmentation after sunlight exposure provide clinical evidence of the role of solar radiation in the pathogenesis of melasma.

Because the wavelength that darken pigment extend from ultraviolet (290-40Onm) into the visible spectrum, protection of the broadest range should be recommended.

Sunscreens are agents that physically or chemically block the penetration of UV light into the skin. Sunscreens usually contain more than one agent to provide greater protection over the range of UVL wavelengths. Products that provide protection in both UVB and UVA are called full or broad spectrum sunscreens.

When used as directed, a sunscreen rated SPF 15 is usually adequate for most skin types. Sunscreens with an SPF greater than 15 may be more protective but are more expensive. They may also increase the possibility of irritation and contact allergy because they contain multiple sunscreen agents in higher concentrations.

Adverse effects to sunscreens are on the whole uncommon. Chemical sunscreen agents, particularly derivatives of PABA, benzophenones, dibenzoyimethanes and anthranilates, can occasionally cause both allergic & photo-allergic contact dermatitis. In addition, PABA containing preparations can stain clothing yellow and cause stinging of the eyes.