Vol. 29, No.1, January 1978 Printed in U.8A.
FERTILITY AND STERILITY Copyright
©
1978 The American Fertility Society
CLINICAL INVESTIGATION OF THE MENSTRUAL CYCLE. I. DIAGRAM OF THE NORMAL MENSTRUAL CYCLE
ANDRE JOLIVET, M.S. JEAN P. GAUTRA Y, M.D.*
Department of Obstetrics and Gynecology, University of Paris Val de Marne, CHIC 94010, Creteil Cedex, France
The clinical definition of normal menstrual cycles has been attempted by using the basal body temperature charts of patients without gynecologic dysfunction who conceived in the following cycle. A second-species linear regression method has been used for statistical comparison of lengths of both follicular and luteal phases. A graphic representation of the equation of the tolerance limit about 46 normal cycles is proposed which can be considered a nomogram of the menstrual cycle.
MATERIALS AND METHODS
The duration of the normal menstrual cycle has been debated for a long time by both endocrinologists and gynecologists involved in clinical practice. The aim of this paper is to define statistically the normal lengths of the two phases of the cycle and thereby to obtain a useful tool for comparing their lengths in normal and pathologic situations.
We defined cycles as clinically normal, in patients with regular menses, without obstetric wastage and/or infecundity and without gynecologic abnormality, if (1) they were of the usual length for that patient; (2) ovulation presumably occurred between day 14 and day 18 of the BBT curve; and (3) conception occurred during the following cycle. In this preliminary study the BBT curve was the only means used to investigate the cycle. A total of 46 cycles that satisfied these criteria were analyzed, and the length of each phase was estimated. The lowest point before the rise in temperature was taken to signify the end of the follicular phase (FP), and the last day before menses was taken as the end of the luteal phase (LP). The lengths of both phases were plotted on a diagram, with ordinates equaling FPs, and abscissas LPs. For statistical comparisons, a second-species linear regression method was used. This method allows demonstration of possible correlations between two random variables, x and y. Two different regression lines were thus compared:
It is generally believed that the mean length of the menstrual cycle is between 26 and 31 days.1 In physiologic conditions, the length of the luteal phase is more constant than that of the follicular phase, i.e., 14 ± 2 days.2 This kind of analysis of the normal menstrual cycle fails to correlate the clinical durations of the two phases with concurrent hormonal profiles. Many clinicians have used measurements ofthe basal body temperature (BBT) to identify the date of ovulation and to characterize the duration of the luteal phase in clinical situations such as the "short luteal" phase. 3 The present communication provides a diagram of the normal menstrual cycle, indicating the lengths of both the follicular and luteal phases; it is hoped that this diagram will help in the clinical diagnosis of other gynecologic disorders.
y =
y + ayx x + axy x
x = X
(x - X) (y
-.YJ
wherey andx are the means of distributions ofthe values of ordinates or abscissas.
Received April 4,1977; accepted May 16, 1977. *To whom reprint requests should be addressed.
40
Vol. 29, No.1
41
CLINICAL INVESTIGATION OF THE MENSTRUAL CYCLE. I FOLLICULAR PHASE (DAYS)
,: J
j(
••
i
'43.,.,
h
Y =(ax). X. (bI) 22
/
Xo
YO
10
.>x
/X,(ay).Y+(by)
.ly
21
I
FERTILITY AND STERILITY Copyright
©
1978 The American Fertility Society
CLINICAL INVESTIGATION OF THE MENSTRUAL CYCLE. I. DIAGRAM OF THE NORMAL MENSTRUAL CYCLE
ANDRE JOLIVET, M.S. JEAN P. GAUTRA Y, M.D.*
Department of Obstetrics and Gynecology, University of Paris Val de Marne, CHIC 94010, Creteil Cedex, France
The clinical definition of normal menstrual cycles has been attempted by using the basal body temperature charts of patients without gynecologic dysfunction who conceived in the following cycle. A second-species linear regression method has been used for statistical comparison of lengths of both follicular and luteal phases. A graphic representation of the equation of the tolerance limit about 46 normal cycles is proposed which can be considered a nomogram of the menstrual cycle.
MATERIALS AND METHODS
The duration of the normal menstrual cycle has been debated for a long time by both endocrinologists and gynecologists involved in clinical practice. The aim of this paper is to define statistically the normal lengths of the two phases of the cycle and thereby to obtain a useful tool for comparing their lengths in normal and pathologic situations.
We defined cycles as clinically normal, in patients with regular menses, without obstetric wastage and/or infecundity and without gynecologic abnormality, if (1) they were of the usual length for that patient; (2) ovulation presumably occurred between day 14 and day 18 of the BBT curve; and (3) conception occurred during the following cycle. In this preliminary study the BBT curve was the only means used to investigate the cycle. A total of 46 cycles that satisfied these criteria were analyzed, and the length of each phase was estimated. The lowest point before the rise in temperature was taken to signify the end of the follicular phase (FP), and the last day before menses was taken as the end of the luteal phase (LP). The lengths of both phases were plotted on a diagram, with ordinates equaling FPs, and abscissas LPs. For statistical comparisons, a second-species linear regression method was used. This method allows demonstration of possible correlations between two random variables, x and y. Two different regression lines were thus compared:
It is generally believed that the mean length of the menstrual cycle is between 26 and 31 days.1 In physiologic conditions, the length of the luteal phase is more constant than that of the follicular phase, i.e., 14 ± 2 days.2 This kind of analysis of the normal menstrual cycle fails to correlate the clinical durations of the two phases with concurrent hormonal profiles. Many clinicians have used measurements ofthe basal body temperature (BBT) to identify the date of ovulation and to characterize the duration of the luteal phase in clinical situations such as the "short luteal" phase. 3 The present communication provides a diagram of the normal menstrual cycle, indicating the lengths of both the follicular and luteal phases; it is hoped that this diagram will help in the clinical diagnosis of other gynecologic disorders.
y =
y + ayx x + axy x
x = X
(x - X) (y
-.YJ
wherey andx are the means of distributions ofthe values of ordinates or abscissas.
Received April 4,1977; accepted May 16, 1977. *To whom reprint requests should be addressed.
40
Vol. 29, No.1
41
CLINICAL INVESTIGATION OF THE MENSTRUAL CYCLE. I FOLLICULAR PHASE (DAYS)
,: J
j(
••
i
'43.,.,
h
Y =(ax). X. (bI) 22
/
Xo
YO
10
.>x
/X,(ay).Y+(by)
.ly
21
I
