Maturitas, l(l979) 159-164 0 Elsevier/North-Holland Biomedical Press
IS THE MENOPAUSAL
159
AGE RAPIDLY CHANGING?
CALLE BENGTSSON, OLOF LINDQUIST and LASSE REDVALL Department of Medicine and Obstetrics and Gynaecology, University of Gtiteborg, Sweden (Received 25 July 1978, accepted 6 October 1978)
A population study of women in Goteborg, Sweden was carried out in 1968-1969. Altogether 1462 women participated (participation rate 90.1%). Five age strata were studied: 38,46, 50, 54 and 60 (women born in 1930, 1922, 1918, 1914 and 1908, respectively). The same women were re-studied in 1974- 1975. Information about menopausal state and, in postmenopausal women, about menopausal age was obtained on both occasions. The information given by the women in 1974-1975 agreed well with the information given in 1968-1969. Very few women started to menstruate again, if the interval since the last menstruation had been 6 mth or longer. The vast majority of the women had a spontaneous menopause. The medians of menopausal age were found to be between 49 yr 7 mth (in women born in 1908) and 50 yr 5 mth (in women born in 1918). There was a tendency towards a continuously increased menopausal age with time as judged from women born in 1908, 1914 and 1918, respectively, but women born in 1922 were found to have a median menopausal age which was more similar to that of the women born in 1908 than that of the women born in 1918. Our study has, thus, not supported the view that the menopausal age is rapidly changing. (Key words: Menopause, Menopausal age, Surgical menopause, Population study)
INTRODUCTION
A population study of women was carried out in Gijteborg, Sweden in 1968-l 969. The same women were restudied 6 yr later, in 1974-1975. Information about menopausal state and, in postmenopausal women, about menopausal age was obtained on both occasions. The purpose of the present paper is to give a description of the menopausal state of middle-aged women in Gijteborg, and to try to find out whether there have been differences in menopausal age during the last years. To what extent amenorrhoea periods of different duration do mean that the women are postmenopausal is also discussed in this paper. MATERIAL AND METHODS
A population study of women Altogether 1462 women participated
was carried out in Giiteborg in 1968-1969 [I]. with a participation rate of 90.1% (Table I). Women
Correspondence to: Docent Calle Bengtsson, Department Goteborg, Sweden.
of Medicine, Sahlgrenska sjukhuset, S-413 45
160 TABLE I Number of participants and participation 1968-1969 and 1974-1975.
rates in the population
studies of women in Gliteborg
in
1974-1975
1968-1969 Age (yr)
n
Participation
38 46 50 54 60 Total
372 431 398 180 81 1462
91.4 90.1 91.0 88.6 83.5 90.1
rate (%)
Age 44 52 56 60 66 Total
(yr)
n
Participation
336 387 351 163 65 1302
90.3 89.8 88.2 90.6 80.2 89.1
rate (%) *
* Of those studied in 1968-1969.
in five age strata were studied: 38,46,50,54 and 60 (women born in 1930, 1922, 1918, 1914 and 1908, respectively). The same women were restudied in 1974-1975 [2]. Altogether 1302 participated on this second occasion, which means 89.1% of those participating in 1968-1969 (Table I). In addition, information was obtained by telephone interviews or postal questionnaires about the non-participants in 1974-1975. Women born on certain days of the month (previously defined multiples of six; 6th, 12th, l&h, etc.) of all months in the years 1930, 1922 and 1918 were called for the study. Of women born in 1914 those who were born on the 6th and 12th of every month were called for the study and of women born in 1908 only those who were born on the 6th of every month. One of the main reasons for the selection of ages was to obtain information about the ages on both sides of the menopause. This method of sampling, together with a high participation rate, assured us that the women studied were representative of women in the general population in the ages studied. Information about menopausal state and, in postmenopausal women, about menopausal age was obtained on both occasions. The information given by the postmenopausal women in 1968-1969 agreed well with the information given by the same women 6 yr later. Questionnaires were used on both occasions, and the information given in the questionnaires was checked in an interview. RESULTS
Interval since lust menstruation as an indicator of a definite menopause
In Table II is shown to what extent an interval, since the last menstruation, of 2 mth or longer means that the menstruations have really ceased. This could be determined as new information about the menopausal state was obtained in 1974-1975. As seen from the table, an interval of 2-5 mth meant that most women had no further menstruations. It is also seen that very few women had further menstruations, if the interval since the last
161 TABLE II Number of women who started to menstruate again after the study 1968-1969 interval between the latest menstruation and the study. Non-menstruating
period (mth)
2 3 4 5 6-11
in relation
to the
Number of women who started to menstruate again Aged 46
Aged 50
o/3 114 315 O/3 2113
l/9 7112 015 l/5 l/26
had been 6 mth or longer. In women aged 50, one out of 26 women with an amenorrhoea period of 6 mth or longer started to menstruate again, which means that only one out of 16 1, 50-yr-old women was falsely postmenopausal when menopause was defined as an amenorrhoea period of 6 mth or longer. With this definition 22,50-yr-old women with true menopause were excluded. If instead an amenorrhoea period of 12 mth or longer had been defined as menopause, another 25 women with true menopause would have been excluded. In women aged 46, two out of 39 women with an amenorrhoea period of 6 mth or longer started to menstruate again, and when using this period of amenorrhoea as a definition of menopause I I women with true menopause were excluded. An amenorrhoea period of 12 mth as a definition had excluded another 11 women with true menopause.
menstruation
Menopausal state in various ages In Table III a description is given of the menopausal state of the women studied in 1968-l 969. It is seen that about 10% of women aged 46-60 had stopped menstruating because of surgical intervention. About 4% of these women had had bilateral oophorectomy and 5-6% had been hysterectomized. If women with surgical menopause are excluded, it was found that about 10% of 46-yr-old women, 44% of 50-yr-old women and 90% of 54-yr-old women had had spontaneous menopause. One of 372 women aged 38 had had spontaneous menopause, and all women aged 60 had had spontaneous or artificial menopause. Menopausal age in different age cohorts Medians of menopausal age in women born in 1908, 1914, 1918 and 1922 could be calculated from the data obtained in 1968-1969 and 1974-1975 and are presented in Table IV. There seemed to be an increase in menopausal age with time when women born in 1908, 1914 and 1918 were compared, but women born in 1922 were found to have an
Age (yr)
38 46 SO 54 60
Year of birth
1930 1922 1918 1914 1908
362 349 168 10 0
97.3 81.0 42.2 5.6 810
1 39 161 146 72
0.3 9.0 40.5 81.1 88.9
%
R
n
%
Postmenopau~
Premenopausal
1 12 34 S 0
n
0.3 2.8 8.5 2.8 0.0
%
2 0 0 0 0
n
Pregnant
0.5 0.0 0.0 0.0 0.0
%
6 20 20 11 5
n
1.6 4.6 5.0 6.1 6.2
%
Oophorectomized
0 11 15 7 3
n
0.0 2.6 3.8 3.9 3.8
%
0 0 0 1 1
n
0.0 0.0 0.0 0.6 1.2
%
Never had menstruations
study in 1968-1969. Hysterectomized
and 1908, respectively) as found in the population
Non-menstruating period 2-5 mth
Menopausal state in women in five age strata (born in 1930,1922,1918,1914
TABLE III
TABLE IV Medians of spontaneous respectively.
menopausal
age in women in Giiteborg born in 1908,1914,
Year of birth
Medians of menopausal age
1908 1914 1918 1922
49yr I mth 50 yr 1 mth 50 yr 5 mth 49 yr 10 mth
1918 and 1922,
menopause than those born in 1914 and 1918. Whether these fluctuations or caused by change only has not yet been established.
earlier
are real
DISCUSSlON
One of the main purposes of the longitudinal population study of women in Gijteborg, Sweden has been to study the effect of the menopause on various factors. It was found that about 90% of the women had a spontaneous menopause, while about 10% stopped menstruating as a consequence of surgical intervention (hysterectomy or bilateral oophorectomy or both). According to the data obtained in the 1968-1969 study there seemed to be a tendency towards delayed menopausal age with time. Thus preliminary data indicated that women born in 1918 had their menopause about 10 mth later than women born in 1908. Complementary data from the study in 1974-1975 confirmed these preliminary results, but it was also then found that women born in 1922 had a lower median menopausal age, which was more similar to that found for women born in 1908. We do not, therefore, believe that the menopausal age is rapidly changing. Smoking habits seem to have influence on the menopausal age [3]. However, smoking habits differed only slightly between women born in 1914, 1918 and 1922 [4], and these differences could not, therefore, explain the differences in menopausal age. As far as we know there are no studies in which the same population has been studied by means of repeated population studies using the same techniques during a long period of time. However, there are other reports from various parts of the world [5], and they do not indicate that the menopausal age is rapidly changing, which is, thus, in agreement with our results. The definition of menopause with regard to duration of the amenorrhoea period has been a matter of controversy. If the definition of the amenorrhoea period is too short, subjects who will start to menstruate again will be included in the postmenopausal group of women. On the other hand, if the definition of amenorrhoea period is too long, a considerable number of women with true menopause will be excluded. In the present paper it is shown for women aged 50 or older that an amenorrhoea period of 6 mth or longer with high accuracy means that the women are postmenopausal, and we have, therefore, used an amenorrhoea period of 6 mth or longer as a definition of menopause in our studies.
164 REFERENCES [ 1] Bengtsson, C., Blohme, G., Hallberg, L., Hallstrom, T., Isaksson, B., Korsan-Bengtsen, K., Rybo, G., Tibblin, E., Tibblin, G. and Westerberg, H. (1973) The study of women in Gothenburg 19681969 - a population study. Genera1 design, purpose and sampling results. Acta Med. Stand. 193, 311-318. [ 21 Bengtsson, C., Hallberg, L., Hlllstrom, T., Hultsborn, A., Isaksson, B., Lennartsson, J., Lindquist, O., Lindstedt, S., Noppa, H., RedvalI, L. and Samuelsson, S. (1978) The population study of women in Gijteborg 1974-1975 - the second phase of longitudinal study. General design, purpose and sampling results. Stand. J. Sot. Med. 6,49-54. [3] Lindquist, 0. and Bengtsson, C. (1979) The effect of smoking on menopausal age. Maturitas 1, 171-173. [4] Bengtsson, C. (1973) Smoking habits in a population sample of women and in women with ischaemic heart disease. Acta Med. Stand. Suppl. 549,60-64. [ 51 Flint, M. (1976) Cross-cultural factors that affect age of menopause. In: Consensus on menopause research. A summary of international opinion, pp. 73-83. Editors: P.A. van Keep, R.B. Greenblatt and M. Albeaux-Fernet. MTP, London, Beccles and Colchester.
IS THE MENOPAUSAL
159
AGE RAPIDLY CHANGING?
CALLE BENGTSSON, OLOF LINDQUIST and LASSE REDVALL Department of Medicine and Obstetrics and Gynaecology, University of Gtiteborg, Sweden (Received 25 July 1978, accepted 6 October 1978)
A population study of women in Goteborg, Sweden was carried out in 1968-1969. Altogether 1462 women participated (participation rate 90.1%). Five age strata were studied: 38,46, 50, 54 and 60 (women born in 1930, 1922, 1918, 1914 and 1908, respectively). The same women were re-studied in 1974- 1975. Information about menopausal state and, in postmenopausal women, about menopausal age was obtained on both occasions. The information given by the women in 1974-1975 agreed well with the information given in 1968-1969. Very few women started to menstruate again, if the interval since the last menstruation had been 6 mth or longer. The vast majority of the women had a spontaneous menopause. The medians of menopausal age were found to be between 49 yr 7 mth (in women born in 1908) and 50 yr 5 mth (in women born in 1918). There was a tendency towards a continuously increased menopausal age with time as judged from women born in 1908, 1914 and 1918, respectively, but women born in 1922 were found to have a median menopausal age which was more similar to that of the women born in 1908 than that of the women born in 1918. Our study has, thus, not supported the view that the menopausal age is rapidly changing. (Key words: Menopause, Menopausal age, Surgical menopause, Population study)
INTRODUCTION
A population study of women was carried out in Gijteborg, Sweden in 1968-l 969. The same women were restudied 6 yr later, in 1974-1975. Information about menopausal state and, in postmenopausal women, about menopausal age was obtained on both occasions. The purpose of the present paper is to give a description of the menopausal state of middle-aged women in Gijteborg, and to try to find out whether there have been differences in menopausal age during the last years. To what extent amenorrhoea periods of different duration do mean that the women are postmenopausal is also discussed in this paper. MATERIAL AND METHODS
A population study of women Altogether 1462 women participated
was carried out in Giiteborg in 1968-1969 [I]. with a participation rate of 90.1% (Table I). Women
Correspondence to: Docent Calle Bengtsson, Department Goteborg, Sweden.
of Medicine, Sahlgrenska sjukhuset, S-413 45
160 TABLE I Number of participants and participation 1968-1969 and 1974-1975.
rates in the population
studies of women in Gliteborg
in
1974-1975
1968-1969 Age (yr)
n
Participation
38 46 50 54 60 Total
372 431 398 180 81 1462
91.4 90.1 91.0 88.6 83.5 90.1
rate (%)
Age 44 52 56 60 66 Total
(yr)
n
Participation
336 387 351 163 65 1302
90.3 89.8 88.2 90.6 80.2 89.1
rate (%) *
* Of those studied in 1968-1969.
in five age strata were studied: 38,46,50,54 and 60 (women born in 1930, 1922, 1918, 1914 and 1908, respectively). The same women were restudied in 1974-1975 [2]. Altogether 1302 participated on this second occasion, which means 89.1% of those participating in 1968-1969 (Table I). In addition, information was obtained by telephone interviews or postal questionnaires about the non-participants in 1974-1975. Women born on certain days of the month (previously defined multiples of six; 6th, 12th, l&h, etc.) of all months in the years 1930, 1922 and 1918 were called for the study. Of women born in 1914 those who were born on the 6th and 12th of every month were called for the study and of women born in 1908 only those who were born on the 6th of every month. One of the main reasons for the selection of ages was to obtain information about the ages on both sides of the menopause. This method of sampling, together with a high participation rate, assured us that the women studied were representative of women in the general population in the ages studied. Information about menopausal state and, in postmenopausal women, about menopausal age was obtained on both occasions. The information given by the postmenopausal women in 1968-1969 agreed well with the information given by the same women 6 yr later. Questionnaires were used on both occasions, and the information given in the questionnaires was checked in an interview. RESULTS
Interval since lust menstruation as an indicator of a definite menopause
In Table II is shown to what extent an interval, since the last menstruation, of 2 mth or longer means that the menstruations have really ceased. This could be determined as new information about the menopausal state was obtained in 1974-1975. As seen from the table, an interval of 2-5 mth meant that most women had no further menstruations. It is also seen that very few women had further menstruations, if the interval since the last
161 TABLE II Number of women who started to menstruate again after the study 1968-1969 interval between the latest menstruation and the study. Non-menstruating
period (mth)
2 3 4 5 6-11
in relation
to the
Number of women who started to menstruate again Aged 46
Aged 50
o/3 114 315 O/3 2113
l/9 7112 015 l/5 l/26
had been 6 mth or longer. In women aged 50, one out of 26 women with an amenorrhoea period of 6 mth or longer started to menstruate again, which means that only one out of 16 1, 50-yr-old women was falsely postmenopausal when menopause was defined as an amenorrhoea period of 6 mth or longer. With this definition 22,50-yr-old women with true menopause were excluded. If instead an amenorrhoea period of 12 mth or longer had been defined as menopause, another 25 women with true menopause would have been excluded. In women aged 46, two out of 39 women with an amenorrhoea period of 6 mth or longer started to menstruate again, and when using this period of amenorrhoea as a definition of menopause I I women with true menopause were excluded. An amenorrhoea period of 12 mth as a definition had excluded another 11 women with true menopause.
menstruation
Menopausal state in various ages In Table III a description is given of the menopausal state of the women studied in 1968-l 969. It is seen that about 10% of women aged 46-60 had stopped menstruating because of surgical intervention. About 4% of these women had had bilateral oophorectomy and 5-6% had been hysterectomized. If women with surgical menopause are excluded, it was found that about 10% of 46-yr-old women, 44% of 50-yr-old women and 90% of 54-yr-old women had had spontaneous menopause. One of 372 women aged 38 had had spontaneous menopause, and all women aged 60 had had spontaneous or artificial menopause. Menopausal age in different age cohorts Medians of menopausal age in women born in 1908, 1914, 1918 and 1922 could be calculated from the data obtained in 1968-1969 and 1974-1975 and are presented in Table IV. There seemed to be an increase in menopausal age with time when women born in 1908, 1914 and 1918 were compared, but women born in 1922 were found to have an
Age (yr)
38 46 SO 54 60
Year of birth
1930 1922 1918 1914 1908
362 349 168 10 0
97.3 81.0 42.2 5.6 810
1 39 161 146 72
0.3 9.0 40.5 81.1 88.9
%
R
n
%
Postmenopau~
Premenopausal
1 12 34 S 0
n
0.3 2.8 8.5 2.8 0.0
%
2 0 0 0 0
n
Pregnant
0.5 0.0 0.0 0.0 0.0
%
6 20 20 11 5
n
1.6 4.6 5.0 6.1 6.2
%
Oophorectomized
0 11 15 7 3
n
0.0 2.6 3.8 3.9 3.8
%
0 0 0 1 1
n
0.0 0.0 0.0 0.6 1.2
%
Never had menstruations
study in 1968-1969. Hysterectomized
and 1908, respectively) as found in the population
Non-menstruating period 2-5 mth
Menopausal state in women in five age strata (born in 1930,1922,1918,1914
TABLE III
TABLE IV Medians of spontaneous respectively.
menopausal
age in women in Giiteborg born in 1908,1914,
Year of birth
Medians of menopausal age
1908 1914 1918 1922
49yr I mth 50 yr 1 mth 50 yr 5 mth 49 yr 10 mth
1918 and 1922,
menopause than those born in 1914 and 1918. Whether these fluctuations or caused by change only has not yet been established.
earlier
are real
DISCUSSlON
One of the main purposes of the longitudinal population study of women in Gijteborg, Sweden has been to study the effect of the menopause on various factors. It was found that about 90% of the women had a spontaneous menopause, while about 10% stopped menstruating as a consequence of surgical intervention (hysterectomy or bilateral oophorectomy or both). According to the data obtained in the 1968-1969 study there seemed to be a tendency towards delayed menopausal age with time. Thus preliminary data indicated that women born in 1918 had their menopause about 10 mth later than women born in 1908. Complementary data from the study in 1974-1975 confirmed these preliminary results, but it was also then found that women born in 1922 had a lower median menopausal age, which was more similar to that found for women born in 1908. We do not, therefore, believe that the menopausal age is rapidly changing. Smoking habits seem to have influence on the menopausal age [3]. However, smoking habits differed only slightly between women born in 1914, 1918 and 1922 [4], and these differences could not, therefore, explain the differences in menopausal age. As far as we know there are no studies in which the same population has been studied by means of repeated population studies using the same techniques during a long period of time. However, there are other reports from various parts of the world [5], and they do not indicate that the menopausal age is rapidly changing, which is, thus, in agreement with our results. The definition of menopause with regard to duration of the amenorrhoea period has been a matter of controversy. If the definition of the amenorrhoea period is too short, subjects who will start to menstruate again will be included in the postmenopausal group of women. On the other hand, if the definition of amenorrhoea period is too long, a considerable number of women with true menopause will be excluded. In the present paper it is shown for women aged 50 or older that an amenorrhoea period of 6 mth or longer with high accuracy means that the women are postmenopausal, and we have, therefore, used an amenorrhoea period of 6 mth or longer as a definition of menopause in our studies.
164 REFERENCES [ 1] Bengtsson, C., Blohme, G., Hallberg, L., Hallstrom, T., Isaksson, B., Korsan-Bengtsen, K., Rybo, G., Tibblin, E., Tibblin, G. and Westerberg, H. (1973) The study of women in Gothenburg 19681969 - a population study. Genera1 design, purpose and sampling results. Acta Med. Stand. 193, 311-318. [ 21 Bengtsson, C., Hallberg, L., Hlllstrom, T., Hultsborn, A., Isaksson, B., Lennartsson, J., Lindquist, O., Lindstedt, S., Noppa, H., RedvalI, L. and Samuelsson, S. (1978) The population study of women in Gijteborg 1974-1975 - the second phase of longitudinal study. General design, purpose and sampling results. Stand. J. Sot. Med. 6,49-54. [3] Lindquist, 0. and Bengtsson, C. (1979) The effect of smoking on menopausal age. Maturitas 1, 171-173. [4] Bengtsson, C. (1973) Smoking habits in a population sample of women and in women with ischaemic heart disease. Acta Med. Stand. Suppl. 549,60-64. [ 51 Flint, M. (1976) Cross-cultural factors that affect age of menopause. In: Consensus on menopause research. A summary of international opinion, pp. 73-83. Editors: P.A. van Keep, R.B. Greenblatt and M. Albeaux-Fernet. MTP, London, Beccles and Colchester.
