Physiological changes associated with the menstrual cycle: a review.

The cyclic hormonal changes that regulate the menstrual cycle are a significant biological influence on the female body, one with both physical and emotional ramifications. Menstruation is governed by tightly orchestrated changes in the levels of ovarian estrogen and progesterone, which produce varying responses in diverse tissues and organs. The skin, the largest organ in the body, is replete with estrogen receptors (in both dermis and epidermis) and to a lesser extent, progesterone receptors. Cyclically fluctuating levels of estrogen and progesterone influence numerous characteristics of the epidermis, including skin surface lipid secretion and sebum production, skin thickness, fat deposition, skin hydration, and barrier function. Dermal collagen content, which contributes to skin elasticity and resistance to wrinkling, is also influenced. Interestingly, estrogen levels also influence skin pigmentation and UV susceptibility, as well as resident microflora. In addition, changing hormone levels across the menstrual cycle produce measurable variations in immune function and disease susceptibility. An understanding of the profound influence that fluctuating estrogen and progesterone levels have on the biological responses of the premenopausal adult woman is critical to optimizing the efficacy of medical therapies in this population.