Evaluation of the effectiveness of a broad-spectrum sunscreen in the prevention of chloasma in pregnant women

Background Chloasma, or melasma, is a pigmentary disorder that can affect between 50% and 70% of pregnant women. During pregnancy, chloasma does not require any particular treatment beside the use of an effective sunscreen and avoiding the use of any photosensitizing products or inappropriate skin care routine. However, there exist very few studies related to the benefits of sunscreens to prevent this dermatosis. Objective The aim of this study was to assess the role of a broad‐spectrum sunscreen in the prevention and treatment of chloasma in pregnant women. Methods We tested the effectiveness and tolerance of a sunscreen composition (SPF 50+, UVA‐PF 28) during a 12‐month clinical trial on 200 parturients. Results The ‘excellent’ tolerance of the sunscreen under evaluation was confirmed. Out of 185 patients who completed the study, only five new cases of chloasma were noted, an occurrence of 2.7%, which is much lower than the 53% previously observed in an usual condition study (same investigators, same geographical area and same time frame). In addition, the clinical effectiveness of the evaluated sunscreen was judged ‘excellent’ by the majority of parturients and by the research dermatologists during all the consultations. It is also worth noting that at 6 months, a clinical improvement was observed in 8 out of 12 volunteers who were affected by a pre‐existing chloasma observed during their inclusion visit. Colorimetric measurements showed that, at the end of their pregnancy, the parturients’ skin was, on average, significantly lightened (increase of parameter L* in 38% cases) and less pigmented (reduction of parameter b* in 50% cases); thus, resulting in a significantly lighter skin colour (increase of ITA° in 69% cases) compared to their inclusion visit. Conclusions This study clearly demonstrates the effectiveness of the well‐tolerated broad‐spectrum sunscreen evaluated, in the prevention of the development of chloasma in pregnant women.