Hormonal dynamics at midcycle: a reevaluation

J Clin Endocrinol Metab. 1983 Oct;57(4):792-6. doi: 10.1210/jcem-57-4-792.


The dynamics of ovarian and pituitary hormone changes during the midcycle period were evaluated. Changes in hormone levels were determined at 2-h intervals for 5 consecutive days during the periovulatory phase of the cycle in five women. During the 50 h preceding the onset of the surge, the rates of increments for estradiol (E2), progesterone (P4), and LH were similar, with doubling times of 57-61 h. The onset of LH and FSH surges was found to occur abruptly (LH doubled within 2 h). They were temporally associated with the attainment of peak E2 levels and occurred 12 h after the initiation of a rapid rise of P4. The mean duration of the surge was 48 h, with a rapidly ascending limb (doubling time, 5.2 h) lasting 14 h accompanied by a rapid decline of E2 and a continued rise of P4. The surge was followed by a peak plateau of gonadotropin levels lasting for 14 h and a transient leveling of P4. The longer descending limb (half-time, 9.6 h), lasting for 20 h, was associated with a second rapid rise of P4, beginning 36 h after surge onset or 12 h before termination of the surge. By using the onset of the LH surge as a reference point, our data provide a relatively precise picture of the hormonal changes preceding the onset of the gonadotropin surge and the temporal relationship between the multiphasic P4 rise and pituitary-ovarian function.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Androstenedione / blood
  • Estradiol / blood*
  • Female
  • Follicle Stimulating Hormone / blood*
  • Humans
  • Hydroxyprogesterones / blood
  • Luteinizing Hormone / blood*
  • Menstruation*
  • Progesterone / blood*
  • Reference Values


  • Hydroxyprogesterones
  • Androstenedione
  • Progesterone
  • Estradiol
  • Luteinizing Hormone
  • Follicle Stimulating Hormone