Grand Challenges in Reproductive Endocrinology

Reproduction is a fundamental aspect of life in all species. In a biological sense, it can be argued that reproduction is the essence of life. Passing on ones genes to the next generation and constantly optimizing the gene pool available for each individual and the species as a whole are vital for continuation and endurance of the species. Reproduction and hormones are intimately connected; thus, hormones are a prerequisite for reproduction and govern nearly all aspects of successful creation in both females and males. Therefore, to numerous scientists, reproductive endocrinology is one of the most fascinating disciplines in science, and it is a pleasure that now finally there is a scientific journal dedicated specifically to reproductive endocrinology. Despite the lack of specific journals dedicated entirely to reproductive endocrinology up until now, this area has had a huge impact on society with first the development of female oral contraceptives around 50 years ago followed by the development of in vitro fertilization techniques to help childless couples in 1970–1980s. Regardless of an enormous amount of literature on sex steroid hormones accumulated over the years, there are constantly new aspects of their function in the body and indeed in the reproductive organs. One aspect that we will hear more about in the coming years is the aging population, in which especially the majority of women will spend up to half of their life in menopause depletion of ovarian sex steroids (1). The consequences on general health including osteoporosis and car-diovascular disease are all aspects within the area of reproductive endocrinology and highlight the need for discussing hormone replacement therapy and/or alternative strategies. The male equivalent testosterone and the effects of testosterone especially in the aging male is also a matter of debate these years, and it is furthermore discussed how to measure testosterone in the clinically most meaningful way (2). Right from the beginning of the IVF era, ovarian stimulation with exogenous FSH preparations has been an indispensable component of successful treatment and numerous studies have been conducted to test different compounds and their effect on the reproductive outcome. Although pregnancy rates of modern day IVF treatment and ART in general have plateaued during the last decade, the journey of optimizing ovarian stimulation is still far from being completed since ongoing pregnancy still occurs in only a fraction of treatment cycles. Whereas the follicular phase of the menstrual cycle has received intense interest …