Sequential classification of endocrine stages during reproductive aging in women: the FREEDOM study.

Objective: Reproductive aging involves complex endocrine changes affecting women's fertility, health, and well-being; however, understanding of the specific changes involved is limited by the lack of detailed quantitative studies. We undertook a thorough study with the aim of characterizing the different endocrine stages involved in female reproductive aging.

Design: FREEDOM is a cohort study designed to determine the endocrine changes during reproductive aging in women.

Comparison between creatinine and pregnanediol adjustments in the retrospective analysis of urinary hormone profiles during the human menstrual cycle.

Measurement of reproductive hormones in urine is a practical way of obtaining large amounts of information; however, there is still controversy on how to overcome problems derived from volume fluctuations between samples. Creatinine adjustment is a widely accepted solution, however, it introduces an extra cost, and large studies involving multiple sequential determinations would benefit from more economical solutions. We determined the value of creatinine adjustment, and compared it with a mathematical method that uses the smoothed profile of pregnanediol (PdG) as a reference to adjust other hormonal markers.