What is happening in the body?

WHAT IS HAPPENING IN THE BODY IN PRE-MENOPAUSE

As the woman approaches the end of her child-bearing years the number of follicles in the ovary has reduced from 250,000 at puberty⁸ to about 10,000 follicles at the age of 45.⁶ At the menopause many of these remaining follicles become atretic (degenerate) without ever achieving an ovulation. This reduced ovarian activity results in decreased levels of the ovarian hormones, oestrogen and progesterone which is the basis of the symptoms of pre-menopause. This can result in:

• Long cycles which may be anovulatory or with delayed ovulation.
• Short cycles due to a short luteal phase, a short follicular phase and early ovulation,⁶ or the luteinized unruptured follicle syndrome (LUF syndrome).¹²

FSH secretion by the pituitary gland is increased due to the absence of the follicular fluid peptide inhibin B, as during normal reproductive life the secretion of FSH is inhibited by inhibin B. The earliest endocrine change marking entry into the menopausal transition is a major fall in inhibin B. However inhibin B is a very difficult and relatively unavailable assay and would not contribute to the staging system.⁵

References:

1. Liu JH, Gass ML; ‘Management of the perimenopause’; 2006; Pub. McGraw-Hill, ISBN 0-0-142281-1
2. Odeblad Erik; ‘The discovery of different types of cervical mucus and the Billings Ovulation Method’; Bulletin of the Ovulation Method Research and Reference Centre of Australia, Vol 21, No3; 3-35; Sept 1994. (on the internet if you google ‘Erik Odeblad, cervical mucus’).
3. Odeblad E, ‘Investigations on the physiological basis for fertility awareness’ page 7; Bulletin for the Ovulation Method Research and ReferenceCentre of Australia, vol 29, no 1, p2-11, march 2002, (internet, Billings Ovulation Method)
4. Flynn A, Brooks M; ‘The Manual of Natural Family Planning’; pages 74-80; 1996; ISBN 0 7225 3115 X
5. Soules MR, Sherman S, Parrot E et al; Executive summary: Stages of Reproductive Aging Workshop (STRAW). Fertil Steril. 2001; 76: 874
6. Flynn A, Worthington W; ‘Teachers Training Manual’; ‘symptothermal multiple index method’ of natural family planning.
7. Harlow S D, Mitchell ES, Crawford S; ‘The ReStage Collaboration: defining optimal bleeding criteriafor onset of early menopausal transition’; Fertil Steril; vol 89, No1, Jan 2008.
8. Alvero Ruben, Schlaff William D; ‘Reproductive endocrinology and infertility, The Requisites in Obstetrics and Gynecology’; 2007, page 229; ISBN-13:978-0-323-04054-9
9. McKinlay SM; ‘The normal menopause tradition: and overview ‘; Maturitas; 1996; 23:137
10. Wallace RB, Sherman BM et al; ‘Probability of menopause with increasing duration of amenorrhea in middle-aged women’; Am. J. Obstet. Gynecol. 135: 1021, 1979.
11. Richardson SJ, Senikas V, Nelson JF; ‘Follicular depletion during the menopausal transition: evidence for accelerated loss and ultimate exhaustion’; J Clin Endocrinol Metab. 1987; 65:1231
12. Brown JB; ‘Types of ovarian activity in women and their significance: the continuum (a reinterpretation of early findings)’; Human Reproduction Update; 2011; Vol 17; No 2; p141-158. (this is a classic article which gives a greater understanding of the menstrual cycle throughout the reproductive life of the woman).
13. Cynthia A. Stuenkel, MD, Margery Gass MD et al; ‘A decade after the Women’s Health Initiative – the experts agree’; Fertility and Sterility; vol 98, no 2; August 2012; p313-314.