Comparison between the different methods developed for determining the onset of the LH surge in urine during the human menstrual cycle.

Purpose: To determine whether an optimal method exists for the detection of the luteinising hormone (LH) surge onset in research datasets of urinary hormonal profiles of menstrual cycles.

Methods: The scientific literature was searched to compare published methodologies for detection of the LH surge onset in urine. Their performance was tested using complete hormonal profiles from 254 ovulatory cycles from 227 women attempting pregnancy (normal regular menstrual cycles; no known infertility).

Increased live birth rate in twin pregnancies resulting from embryo assistance.

Objective: To estimate why the live birth rate per implanted embryo is higher in twin than in singleton pregnancies.

Methods: Data from 1,159 singleton and 523 dichorionic twin pregnancies, obtained after assisted conception, were included. To account for the higher live birth rate observed in twin pregnancies, two possibilities were considered: embryo collaboration and assistance.

Levels of urinary human chorionic gonadotrophin (hCG) following conception and variability of menstrual cycle length in a cohort of women attempting to conceive.

Objectives: To define the variability of menstrual cycle length and contribution of follicular and luteal phases to overall cycle variability, and to examine the rise in urinary hCG in early pregnancy.

Methods: Menstrual cycle study. Urine samples from 101 women (recruited from two south-east counties in the UK) were assayed to determine day of luteinising hormone (LH) surge, lengths of follicular and luteal phases and correlations with total menstrual cycle length.

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.