HORMONAL CHANGES AND SKIN 317 14 Estradiol 12 Progesterone Dry skin te 10 / , .. ·, ' \ 8 \ \ I A 6 I ... " ,• f � / ' \ \ 4 \ ' z 2 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Menstrual Rlase Protif erative Riase Secretory Riase Figure 4. Skin moisturization in relation to the menstrual cycle. Most subjects exhibited the driest skin in the first week of the cycle. 14 - Estradiol 12 Progesterone i 10 ,. ✓ .._ Skin surface lipids I I I 8 \ I 0 6 4 z ,, 2 / 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Menstrual Rlase A'olif erative Alase Secretory Rlase Figure 5. Skin surface lipids in relation to the menstrual cycle. There appear to be two peaks: days 12-15 and days 20-25 of the cycle. These peaks appear to coincide with the appearance of estradiol levels in the blood. Skin micro/fora. As observed in Figure 6, the highest microbiological count was around days 20-25. Staphylococcus epidermidus was the most prevalent organism, and no consistent shift in bacterial population was observed over the course of the month. UV sensitivity. The histogram of the number of panelists exhibiting the least MED at a day in the cycle versus the days in the cycle is displayed in Figure 7. The least MED is indicative of high UV susceptibility. As observed in the graph, there appears to be a higher susceptibility between days 20 and 28 of the menstrual cycle. Studies conducted

318 JOURNAL OF COSMETIC SCIENCE j § 14 - - - - - - - Estradiol 12 I - - - - - Progesterone 10 ---Microflora 8 6 4 2 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Menstrual Ftlase A'olif erative Ftlase Secretory R1ase Figure 6. Skin surface microflora in relation to the menstrual cycle. The highest microbial count was around days 16-22 of the monthly hormonal cycle. This study implies a correlation between the bacterial population and sebum production on the skin surface. 14 2 ____________ _.,,, I I · · · · · · · Eetradiol - • - - - Projeaterone -High UV Susceptibility month 1 High UV Suaceptlbllity month2 0 2 4 6 8 10 12 14 16 18 20 22 24 28 28 30 Manatrual Ruma Rolerativa Fhue Secramry R181a Figure 7. UV susceptibility in relation to the menstrual cycle. Several subjects exhibited a lower MED and thereby a higher UV susceptibility between days 20 and 28 of the menstrual cycle. In this study UV susceptibility appears to be concurrent with an impaired barrier. It is possible that this variation in MED is due to the combined effect of several factors, including hormonal levels and stratum corneum integrity. by Jemec and Heidenheim (23) indicate an increased UV-induced inflammation fol­ lowing topical application of estrogen, but they observe no significant change in UV response in correlation with the blood levels of estrogen. DISCUSSION The menstrual cycle starts with the menstrual phase on days 1 to 6 when the thickened