Key words
breastfeeding - maternity hospitals - infant nutrition - baby-friendly hospital -
lactation
Schlüsselwörter
Stillen - Entbindungskliniken - Säuglingsernährung - babyfreundliches Krankenhaus
- Muttermilch
Introduction
In recent years there has been an increase in the number of reports about the importance
of breastfeeding for health politics, in industrial countries as well [10]. It has been shown that children who were breastfed have a lower risk of acute otitis
media, gastroenteritis, respiratory infections, atopic dermatitis, asthma, overweight,
type I and type II diabetes, leukemia, sudden infant death and necrotic enterocolitis,
particularly for premature births [11]. A clearly positive effect of breastfeeding on the health of the mother is also
acknowledged. Breastfeeding reduces the probability of developing type II diabetes,
metabolic syndrome, breast and ovarian cancer and postpartal depression [10], [11], [25]. The costs of non-breastfeeding compared with six months of breastfeeding for 90 %
of all children in the USA in 2001 were estimated
to be 13 billion US dollars. A conservative estimate indicates that 911 additional
infant deaths could have been prevented [1]. For the realisation of successful breastfeeding the obstetrics team plays a key
role in advising and caring for the mother and newborn child during pregnancy, all
aspects of the actual childbirth and in the first days postpartum. Hospital care following
birth influences the frequency and duration of breastfeeding. In general, together
with baby-friendly initiatives of the maternity clinic, the “10 steps for successful
breastfeeding” formulated by the WHO and Unicef structure and promote the process
of lactation and the duration of breastfeeding [7], [19].
After a low point in the frequency of breastfeeding in the 1970s, beginning around
1980 the frequency and duration in Germany began increasing [16].
The objective of the present study was to provide answers to the questions: Which
women in the Freiburg birth collective breast fed their children for at least six
months after birth? Which socio-demographic variables had positive and which had negative
influences upon breastfeeding? What are the influences of the place of birth, type
of birth and professional care?
Methods
A prospective, longitudinal multi-centre cohort study was performed within the scope
of two doctoral theses [12], [21].
Between August and December 2007 the two doctoral candidates interviewed a total of
443 women who had recently given birth to a living child according to a standard format,
219 of these in the University Gynaecological Clinic (Universitäts-Frauenklinik),
216 in the Evangelical Diakonie Hospital (Diakonie-Krankenhaus) and 8 in the Geburtshaus
Mayenrain in Freiburg. The study was approved by the ethics commission of the university
hospital. The women who had recently given birth were given information in printed
form and requested to sign a declaration of consent. Exclusion criteria were age under
the age of 18, lacking knowledge of the German language, lack of a telephone, medical
contra-indications against breastfeeding and multiple births. The 443 women who had
recently given birth comprised approximately one third of the entire number of births
in these three facilities during the recruiting period. The University Gynaecological
Clinic and the Diakonie Hospital
maternity hospitals are accredited by the baby-friendly hospital initiative. The Geburtshaus
Mayenrain is under the direction of freelance midwives.
The first interview was held at time T0 on the day after giving birth and was conducted
by a doctoral candidate in the patientʼs hospital room. The women from the Geburtshaus
were visited at home on the first day after giving birth. Following a preliminary
study for the optimisation of the standard interview format the mean time of the first
interview was 10 minutes. After three (T1), 6 (T2) and 12 (T3) months the women who
had taken up breastfeeding were interviewed by telephone according to a structured
format. The last interview was held after the patient had stopped breastfeeding or
the child had reached the age of 12 months. The mean time of the telephone interviews
at time T1 was 11 minutes, at time T2 7 minutes and after 12 months 6 minutes. Patients
who could not be reached by telephone were notified in writing or the attending physician
contacted. 11 patients prematurely discontinued their participation in the study:
6 could no longer be reached, 3 relocated to
foreign countries outside of Europe, one child was left with a foster family, and
one woman decided not to continue participating. The follow-up quota was thus 97.5 %.
All “drop outs” were evaluated as having stopped breastfeeding.
The statistical analysis was carried out with the SAS 9 software package. The bivariate
analysis took place on the basis of contingency tables and with the aid of the χ2 test. The significance limit was defined to be 5 %. The logistic regression analysis
was carried out as multivariate, binary with backward elimination in order to assess
the different variables influencing the results.
Results
In our collective 92 % (409 of 443) took up breastfeeding and 8 % (34 of 443) decided
in favour of primary delactation. Bad experience with earlier births was cited as
the most frequent reason. At time T1 (after three months) 74 % of the women were still
breastfeeding, at time T2 (after six months) 61 % and at time T3 (after 12 months)
28 %.
[Fig. 1] shows the decline in the breastfeeding quota as a Kaplan-Meier curve, with the steepest
decline after two months. The most frequent reason why the women beginning breastfeeding
stopped this was “presumably too little lactation” (24 %), followed by “the child
did not want anymore” (14 %) and “the mother did not want anymore” (14 %). Other reasons
were too much stress (11 %), health problems (9 %), breast problems (8 %), “it was
time to stop” (6 %), breastfeeding confusion (5 %), taking up employment (5 %) and
bad experience previously (4 %).
Fig. 1 Number of breastfeeding women from delivery (0 months) to 1 year.
At time T2 (after six months) the bivariate analysis stratifies the status patient
continuing breastfeeding versus patient stopped breastfeeding according to the following
results ([Table 1]):
Table 1 Breastfeeding and not breastfeeding at time T2 (after six months).
|
Parameter
|
Breastfeeding
|
Not breastfeeding
|
p value
|
|
n
|
%
|
n
|
%
|
|
n. s.: not significant, * significant, ** highly significant, *** very highly significant.
|
|
Age
|
|
|
|
|
|
|
|
25
|
46.3 %
|
29
|
53.7 %
|
**
|
|
|
160
|
67.8 %
|
76
|
32.2 %
|
0.002
|
|
|
85
|
72.7 %
|
32
|
27.4 %
|
|
|
Migratory background
|
|
|
|
|
|
|
|
81
|
60.9 %
|
52
|
39.1 %
|
n. s.
|
|
|
189
|
69.0 %
|
85
|
31 %
|
0.1322
|
|
Educational level
|
|
|
|
|
|
|
|
12
|
35.3 %
|
22
|
64.7 %
|
***
|
|
|
126
|
58.6 %
|
89
|
41.4 %
|
< 0.0001
|
|
|
127
|
83 %
|
26
|
17 %
|
|
|
Premature birth
|
|
|
|
|
|
|
|
24
|
55.8 %
|
19
|
44.2 %
|
n. s.
|
|
|
246
|
67.6 %
|
118
|
32.4 %
|
0.1695
|
|
Gravidity
|
|
|
|
|
|
|
|
127
|
69.8 %
|
55
|
30.2 %
|
n. s.
|
|
|
143
|
63.6 %
|
82
|
36.4 %
|
0.2241
|
|
Parity
|
|
|
|
|
|
|
|
146
|
67.9 %
|
69
|
32.1 %
|
n. s.
|
|
|
124
|
64.6 %
|
68
|
35.4 %
|
0.5463
|
|
Mode of delivery
|
|
|
|
|
|
|
|
136
|
68.7 %
|
62
|
31.3 %
|
|
|
|
19
|
73.1 %
|
7
|
26.9 %
|
|
|
|
69
|
71.1 %
|
28
|
28.9 %
|
*
|
|
|
46
|
53.5 %
|
40
|
46.5 %
|
0.038
|
|
Previous experience
|
|
|
|
|
|
|
|
99
|
72.3 %
|
38
|
27.7 %
|
**
|
|
|
19
|
63.3 %
|
11
|
36.7 %
|
|
|
|
5
|
26.3 %
|
14
|
73.7 %
|
0.004
|
|
|
236
|
68.8 %
|
107
|
31.2 %
|
*
|
|
|
10
|
58.8 %
|
7
|
41.2 %
|
0.0434
|
|
|
24
|
51.1 %
|
23
|
48.9 %
|
|
|
|
57
|
53.3 %
|
50
|
46.7 %
|
**
|
|
|
213
|
71 %
|
87
|
29 %
|
0.001
|
|
|
178
|
60.5 %
|
116
|
39.5 %
|
***
|
|
|
87
|
80.6 %
|
21
|
19.4 %
|
0.0003
|
|
|
242
|
69.5 %
|
106
|
30.5 %
|
**
|
|
|
28
|
47.5 %
|
31
|
52.5 %
|
0.0015
|
|
Experience with breastfeeding at T1
|
|
|
|
|
|
|
|
224
|
75.2 %
|
74
|
24.8 %
|
***
|
|
|
19
|
52.8 %
|
17
|
47.2 %
|
|
|
|
22
|
32.4 %
|
46
|
67.7 %
|
< 0.0001
|
|
|
199
|
76.8 %
|
60
|
23.2 %
|
***
|
|
|
66
|
46.2 %
|
77
|
53.9 %
|
0.0005
|
|
Motivation for breastfeeding
|
|
|
|
|
|
|
|
164
|
89.6 %
|
19
|
10.4 %
|
***
|
|
|
82
|
77.4 %
|
24
|
22.6 %
|
|
|
|
18
|
50 %
|
18
|
50 %
|
< 0.0001
|
|
|
22
|
39.3 %
|
34
|
60.7 %
|
***
|
|
|
242
|
89.6 %
|
28
|
10.4 %
|
< 0.0001
|
|
|
215
|
69.6 %
|
94
|
30.4 %
|
*
|
|
|
45
|
54.2 %
|
38
|
45.8 %
|
0.018
|
|
|
36
|
62.1 %
|
22
|
37.9 %
|
n. s.
|
|
|
42
|
63.6 %
|
24
|
36.4 %
|
|
|
|
191
|
68.2 %
|
89
|
31.8 %
|
0.7131
|
|
|
7
|
46.7 %
|
8
|
53.3 %
|
n. s.
|
|
|
258
|
66.7 %
|
129
|
33.3 %
|
0.1849
|
|
|
243
|
68.5 %
|
112
|
31.5 %
|
n. s.
|
|
|
3
|
42.9 %
|
4
|
57.2 %
|
|
|
|
3
|
37.5 %
|
5
|
62.5 %
|
0.1004
|
|
|
17
|
51.5 %
|
16
|
48.5 %
|
n. s.
|
|
|
253
|
67.7 %
|
121
|
32.4 %
|
0.0915
|
|
Place of birth
|
|
|
|
|
|
|
|
121
|
60.2 %
|
80
|
39.8 %
|
**
|
|
|
141
|
71.2 %
|
57
|
28.8 %
|
|
|
|
8
|
100 %
|
0
|
|
0.008
|
|
|
217
|
69.1 %
|
97
|
30.9 %
|
*
|
|
|
52
|
56.5 %
|
40
|
43.5 %
|
0.0340
|
|
Postpartal care
|
|
|
|
|
|
|
|
207
|
67 %
|
102
|
33 %
|
**
|
|
|
8
|
34 %
|
15
|
66 %
|
0.0021
|
|
Postpartal care
|
|
|
|
|
|
|
|
234
|
69.4 %
|
103
|
30.6 %
|
**
|
|
|
31
|
47.7 %
|
34
|
52.3 %
|
0.0012
|
Older women frequently continue breastfeeding for a statistically significant longer
time than younger mothers.
Mothers without a migratory background breast fed more frequently for up to six months
than women of migratory background. This difference indicates a tendency however it
is not statistically significant.
A decisive factor is the level of education. 64.7 % of women not completing their
schooling or only with a secondary school education, 41.4 % of women with a school
leaving certificate and only 17 % of women with 11 or more years of education stopped
breastfeeding after 6 months.
Children born after a normal time of pregnancy tend to still be breastfed after six
months (37 + 1 week of pregnancy). However, in view of the low number of premature
births (n = 43) this difference is not significant.
The influence of the number of pregnancies and the parity is not significant.
In respect of the mode of birth, a statistically significant negative correlation
is recognisable for primary caesarean delivery.
The influence of subjective experiences with the breastfeeding of a previous child
is significant. Women with positive earlier experiences are more likely to breastfeed
another child than women with mixed earlier experiences or altogether negative experiences.
The breastfeeding situation on the first postpartal day has a considerable influence
upon the duration of breastfeeding. Women who, following birth, can nourish their
babies on the breast alone frequently breastfeed their children for longer than six
months. When glucose solution is orally administered in addition, the percentage of
children breastfed over a longer time is lower. With formula supplementation nutrition
the percentage of children breastfed longer than six months declines significantly.
The correlation between the use of breastfeeding aids (such as milk pumps, bottle
feeding, nipple shields or mamilliforms) on the first day after birth and the duration
of breastfeeding is also statistically significant. When no breastfeeding aids are
required, the percentage of children breastfed for longer than six months is greater
than for newborn children requiring breastfeeding aids.
A highly significant correlation was found for children who are given a pacifier (dummy)
at the age of three months. Children without a pacifier are more frequently breastfed
longer than six months than children who are given a pacifier.
The correlation of the intention to breastfeed on the day after birth with a longer
duration of breastfeeding is statistically significant. Women who fully intend to
breastfeed are far more likely to breastfeed after six months than those not planning
to breastfeed.
If the breastfeeding period is positively experienced after three months there is
a greater probability of breastfeeding children for longer than six months. When this
is experienced only positively, many children are still breastfed after six months.
With mixed experiences the number is less. With largely negative experiences with
breastfeeding after three months, only relatively few children are breastfed longer
than six months.
When the actual experience of breastfeeding coincides with expectations after three
months, this also has a positive influence on the duration of breastfeeding.
The motivation after three months shows a statistically significant correlation with
the duration of breastfeeding. Very strongly motivated women frequently breastfeed
for longer than six months; whereas poorly motivated women rarely breastfeed their
children longer than six months.
A highly significant factor is uncertainty on the part of the mother whether the amount
of milk produced at time T1 (after three months) is sufficient or not. When there
is no doubt the majority of mothers breastfeed longer than six months and when there
is uncertainty only 39.3 % of the women.
When the partner supports the decision to breastfeed there is a recognisable correlation
with longer durations of breastfeeding. Compared with women whose partners do not
support the decision to breastfeed, women with supportive partners are more likely
to breastfeed their children longer than six months.
No statistically significant correlation exists between an illness of the mother and
the duration of breastfeeding.
A postpartum depression was diagnosed with 15 women at the time of the interview after
three months. Seven of these women breastfed their children longer than six months,
compared with the majority of women without postpartum depression. In view of the
small number of cases, this difference is not significant.
As with prematurely born children the probability of stopping breastfeeding for children
with other peculiarities, such as congenital abnormalities or diseases, after up to
six months is greater. Compared with healthy children, the majority of whom are breastfed
longer than six months, less than half of the children with congenital abnormalities
and even less children with other diseases were breastfed for longer than six months.
Here again, in view of the small number of cases this difference is not statistically
significant.
A consideration of the place of birth can be correlated with the duration of breastfeeding.
Children born in the University Gynaecological Clinic are less frequently breastfed
longer than six months than children born in the Diakonie Hospital. This difference
is significant and results from the different patient groups. The duration of breastfeeding
was longer for all children born in the Geburtshaus Mayenrain. However, in view of
the small number of cases (n = 8) no statistical evaluation is possible.
Women who were satisfied with the care provided by the maternity hospital were more
likely to breastfeed longer than six months than women who were not satisfied with
the care provided. The postpartum follow-up care also influences the duration of breastfeeding.
Women with postpartum care by a midwife showed a higher probability of breastfeeding
longer than six months. When women experienced the postpartum care positively the
percentage breastfeeding their children six months was significantly higher than for
women with an unsatisfactory postpartum care situation.
In the multivariate logistic regression two variables were found to have an independent
significant positive influence and two variables a negative influence on the duration
of breastfeeding:
-
Whether the mother has studied more than 11 years (p =< 0.0001, odds ratio 3.927,
95 % CI 2.350–6.562),
-
satisfaction with the care in the maternity hospital (p = 0.0050, odds ratio 2.091,
95 % CI 1.250–3.499),
-
no postpartum care by a midwife (p = 0.0144, odds ratio 0.307, 95 % CI 0.119–0.790),
and
-
negative experience with breastfeeding (p = 0.0287, odds ratio 0.433, 95 % CI 0.204–0.917).
Discussion
8 % of the women in our Freiburg birth collective of 2007 decided in favour of primary
delactation. This rate agrees roughly with the statistics given in the literature
for Germany. The SuSe study of 1717 children born in Germany in 1997/1998 [14] reported a primary delactation rate of 9 %. More recent data from Bavaria [15] report a primary delactation rate of 10.5 % for 3822 participating women. A significantly
different primary delactation rate of only 3 % was reported for 2005 children born
in a Hamburg hospital [4]. This conspicuously low delactation rate can possibly be attributed to the particular
group of women giving birth in a hospital located in a prosperous neighbourhood.
While the initiation rate for breastfeeding is high in our study a significant decline
was observed in the further course of the study, most noticeably after around eight
weeks ([Fig. 1]). Nevertheless, the breastfeeding quota of 74 % after three months is significantly
higher than the 65 % reported in 1998 [14] and the 65 % reported in Bavaria [15]. In our collective 61 % of the mothers are still breastfeeding after six months,
while the SuSe study reported 48 % and the Bavarian data reported 52 %.
Our study indicates that even after 12 months 28 % of the infants are at least partly
breastfed. By comparison, the study of 10 years ago reported that this had declined
to 13 % [14]. Following the low point of the breastfeeding frequency in the 1970s and a renaissance
of breastfeeding in the 1980s and 1990s, there are now indications of a possible trend
to longer durations of breastfeeding.
The most frequently given reasons for stopping breastfeeding revealed by our study
were too little lactation (23 %) and the child or mother did not want anymore (14 %
each). Identical figures of 14 % of mothers and of children who did not want breastfeeding
anymore were reported in the Hamburg study [23]. In this study also, the most important reason given was not having sufficient milk
(44 %).
In our collective older mothers breastfed longer than six months significantly more
frequently than younger women. This effect is apparent in all published studies, for
example in the prospective cohort study on breastfeeding in Bavaria [22] or in a Canadian cohort study with 856 mother-child pairs published in 2006 [2].
Women with a migratory background practice primary delactation less frequently, but
often feed over a shorter time. Comparisons with other studies are very difficult,
as the composition of the collectives is very different and this factor can have very
different influences on adapting to the country of immigration. A similar result was
also described in the Bavarian study, with longer durations of breastfeeding for mothers
born in Germany [22].
The sole demographic factor was the level of education of the mother, which was also
shown to be highly significant in the multivariate analysis. Women with the qualification
to undertake university studies breastfeed significantly longer than women with a
secondary school education or women not completing their schooling. This effect is
observed in all studies [2], [15], [20], [22].
For the 43 premature births in our study collective a tendency towards breastfeeding
shorter than six months was observed. In view of the small number of cases, this difference
is not statistically significant. In the Bavarian study the adjusted odds ratio for
the primary delactation of premature births was reported as 3.04 [15]. Establishing satisfactory breastfeeding following a premature birth thus appears
to be a particular challenge. A case control study of interest from the Netherlands
reported a 63 % rate of breastfed prematurely born infants released early from hospital
care with a stomach tube, compared with only 36 % for prematurely born infants following
a longer hospital stay [18]. The positive influence of a high level of education for the mother on the breastfeeding
of prematurely born infants (60 % of very small prematurely born infants were exclusively
breastfed when discharged) is reported in a study
from Denmark [27]. Exclusively breastfeeding a prematurely born infant is more difficult than the
breastfeeding of a child born after a normal pregnancy, but is particularly positive
for the childʼs healthy development. The literature reports lower breastfeeding rates
for prematurely born infants compared with infants born after a normal pregnancy,
for example in the Bavarian study of Kohlhuber et al. [15].
Positive experience with the breastfeeding of previous children appears to favour
longer durations of breastfeeding in women who have borne children previously. Thus,
for example, Schwegler et al. [22] report a statistically significant correlation between longer durations of breastfeeding
and mothers who have experience with breastfeeding. By contrast, our study indicates
that there is no relevant difference between women pregnant for the first time and
women who have previously borne children.
Our study revealed the influence of the mode of birth on breastfeeding. Spontaneously
delivered children, vaginally operative deliveries, and secondary caesarean deliveries
show a high percentage of breastfeeding for longer than six months. Children delivered
by elective caesarean section showed a statistically significant lower rate of breastfeeding
for more than six months. A possible explanation for this difference could be the
higher number of ill children, premature births and mothers with pre-existing problems
which preclude breastfeeding [9], [24]. Another possibility could be the influence of the lower endogenic release of oxytocin
in the group of women delivering by elective caesarean section. An enhanced rate of
prematurely stopped breastfeeding has also been reported in Italy by Zanardo et al.
[28] and by Haugen et al. in Norway [8]. As found in our study,
the Bavarian study [22] reports a longer duration of breastfeeding for spontaneously delivered children;
in the multivariate analysis, however, this was no longer significant. However, in
this study only two groups were formed: spontaneously delivered children versus vaginally
operative and elective and secondary caesarean section deliveries in a single category.
In the present study the mode of birth had no independent significant influence on
the duration of breastfeeding (see multivariate analysis).
The negative influences of formula supplementation in the first days of the infantʼs
life and of problems and the necessity of breastfeeding aids has been described many
times in the literature. In the Bavarian study [22] breastfeeding aids during the first days of the infantʼs life and problems with
breastfeeding showed a highly significant correlation with shorter durations of breastfeeding.
The negative influences of formula supplementation during the first days and of using
a pacifier are also reported in the USA studies [3], [6]. The Norwegian study also shows the negative influence of formula supplementation
during the first days of life [8]. These data prove that formula supplementation during the first days of life must
in any case be made dependent upon existing medical indications and may in no case
represent a routine procedure. The observation of shorter
durations of breastfeeding when breastfeeding aids are used in the first days of life
can certainly be due to the existence of problems and has also been reported in other
studies [17], [20].
As was found in our study, a significant negative correlation between the use of a
pacifier and the duration of breastfeeding was also found in other studies [20], [22]. However, Schwegler et al. and Roig et al. investigated the use of a pacifier in
the first days of the infantʼs life; that is, in the phase of initiating breastfeeding.
In our study we investigated the influence of a pacifier at the age of three months.
It is understandable that women who experience breastfeeding positively breastfeed
their children longer than women who experience problems with breastfeeding. The positive
correlation is significant in both the bivariate and the multivariate analysis. Decisive
for the well-being of the mother and child is the absence of stress and doubts. The
vicious circle created by the very common doubts about the amount of milk and the
resulting stress which restricts the release of oxytocin and the ensuing inhibition
of the let-down reflex is problematical.
The importance of the partnerʼs support of breastfeeding has been frequently described
in the literature. The Bavarian study [15] and the Hamburg study [13] indicated the clear influence of the partnerʼs support on the duration of breastfeeding.
Mothers who are ill without medical reasons for rejecting breastfeeding should be
helped to breastfeed satisfactorily. For mothers with postpartum depression a complex
interaction may possibly exist between breastfeeding, breastfeeding problems and the
outbreak of the illness. The observation that depressive mothers stop breastfeeding
earlier is supported by a number of published studies [2], [5], [26].
The differences between women giving birth to children in the University Gynaecological
Clinic, the Diakonie Hospital and the midwivesʼ practice revealed by our study are
certainly attributable to differences in the groups of mothers at the different places.
The multivariate analysis shows that the place of birth has no independent significant
influence upon successful breastfeeding. The multivariate analysis shows a significant
correlation between the duration of breastfeeding and satisfaction with the care provided
by the maternity hospital. In the Bavarian study [22] a positive correlation was found between outpatient birth and a longer duration
of breastfeeding. The positive correlation was attributed to a larger percentage of
women with greater interest in questions of health in the group of women with outpatient
child delivery. Equally relevant is the follow-up care by a midwife. This positive
correlation with a longer duration of
breastfeeding was shown by the multivariate analysis.
Conclusions
Our study clearly shows the effects of different variables on breastfeeding. These
factors can be influenced and include: more information about healthy infant nutrition
and the disadvantages of not breastfeeding, particularly for young parents and relatively
uneducated social segments, the creation of a satisfactory puerperium atmosphere,
avoiding supplemental nutrition without medical indication in the first days of life,
and dispelling doubts concerning the amount of breast milk. The care provided by the
maternity hospital should be provided by properly trained personnel (midwives, obstetricians
and paediatric specialists) to the satisfaction of the mother, so that positive experiences
promote breastfeeding. Following the normally brief hospital stay and the midwifeʼs
support of and advice to the mother, the advice of gynaecologists and neonatologists
with experience in breastfeeding is also urgently required.
Impact for Clinical Practice
Impact for Clinical Practice
Gynaecologists must have a well-founded knowledge of the advantages and management
of breastfeeding. Particularly experience-based care should be possible in the following
situations: with young mothers, women from relatively uneducated social segments,
illness or separation of the mother from the newborn infant, and following caesarean
deliveries.
Acknowledgements
We wish to express our sincere gratitude to Professor Walter Schuth for his advice
with the development of the standard interview format and discussion of the results.
Our thanks are also due to Ms. Heike Tröndle for the preparation of the manuscript.
