Time Intervals during the Menstrual Cycle with Special Reference to the Long Follicular Phase
James B. Brown
Endocrinologist and researcher, James Brown outlines the timing of events during the menstrual cycle as it pertains to hormone levels.

The Fertile Period
John T. France
This article affirms modern science and how far they have come to determine the duration of the fertile period. However, France emphasizes the need to gain a more detailed knowledge of the survival of the spermatozoa within the female reproductive system and the lifespan of the ovum following ovulation in order to have a true understanding of fertile phases.

The Occurrence of Ovulation at the Midcycle
Thomas W. Hilgers, Ann M. Prebil, Susan K. Hilgers, and K. Diane Daly
It is common for gynecologists to refer to "midcycle" ovulation of women. This comes from the known average 28 day menstrual cycle and the estimated ovulation beginning on the 14th day. This article uses Natural Family Planning data to criticize this concept of the midcycle on day 14.

Assessment of the Fertile and Sterile Phases of the Menstrual Cycle
Rudolf F. Vollman
Dr. Vollman describes some of the important facts of women's reproductive physiology and analyzes their significance in respect to Natural Family Planning. He references the original Basal Body Temperature Method and the approach of the Billings Ovulation Method.

The Pre-Menstrual Phase of the Menstrual Cycle
Rudolf F. Vollman
Dr. Vollman uses this article to compare the three clinical signs and symptoms of a menstrual cycle. Vollman finds the length of the premenstrual phase to be different based on measurement by cervical mucus, intermenstrual pain, and Basal Body Temperature.

Postmenstrual Phase of the Menstrual Cycle
Rudolf F. Vollman
Dr. Vollman, former head of Obstetrics and Perinatal Research at the National Institutes of Health, brings the discussion back to basics as he shares his research on the menstrual cycle. Menstrual charts are provided to further the understanding of a woman's reproductive physiology.

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