# functions of oestrogen > Estrogen is an important sex steroid hormone which serves an important role in the regulation of a number of biological functions, including regulating bone density, brain function, cholesterol mobilization, electrolyte balance, skin physiology, the cardiovascular system, the central nervous system and female reproductive organs[[(Chen et al., 2019)#^83im1]] - [[oestrogen promotes development and maintenance of female reproductive structures]] - [[oestrogen promotes development and maintenance of secondary sex characteristics]] - [[oestrogen increases protein anabolism]] - [[oestrogen lowers blood cholesterol]] - [[oestrogen prepares the uterus for pregnancy by stimulating the repair and thickening of the endometrium]] - [[moderate levels of oestrogen inhibit the release of GnRH, FSH, and LH]]