title: Seasonal influence of diurnal rhythms in the onset of the plasma luteinizing hormone surge in women.
abstract: The time of the LH surge onset in plasma was detected in 75 human cycles. The preovulatory LH surge began between midnight and 0730 h in two thirds of the patients. According to the season of study, the LH surge began between 1030 and 2215 h in 52.4% of the spring cycles compared with 12.9% of the cycles studied during other seasons (P less than 0.001). The highest frequency of the LH surge occurrence over a 3-h time interval was 1500 +/- 1.5 h during the spring cycles (28.6%) and 0300 +/- 1.5 h (42.5%) during the other seasons. It was estimated that ovulation occurred primarily in the morning during the spring and primarily in the evening during autumn and winter.
mesh_terms: D000328:Adult; D002940:Circadian Rhythm; D004958:Estradiol / Q000097:blood; D005260:Female; D006801:Humans; D008183:Luteal Phase; D007986:Luteinizing Hormone / Q000097:blood*; D012621:Seasons
chemical_list: D004958:Estradiol; D007986:Luteinizing Hormone