Geographical distribution of publications in Human Reproduction and Fertility and Sterility in the 1990s*

Jan A.M. Kremer1,3, Didi D.M. Braat1 and Johannes L.H. Evers2,5

1 Department of Gynaecology and Obstetrics, University Hospital Nijmegen and 2 Department of Gynaecology and Obstetrics, University Hospital Maastricht, The Netherlands

Abstract

Curious about the geographical distribution of publications in reproductive medicine, we compared the numbers of publications in Human Reproduction (HR) and Fertility and Sterility (F&S). The annual number of publications from the individual countries was obtained by searching the Medline database using the internet provider PubMed. The data were analysed and normalized to population size, gross domestic product (GDP) and total number of Medline publications. The 8511 publications of both journals in the 1990s came from 56 countries. The number of publications per year was increasing in HR and remained constant in F&S. In absolute numbers, the UK produced the most publications in HR (21%) and the USA in F&S (45%) as well as in both journals together (28%). Relatively, Israel was the most productive country per million inhabitants (8.4 ± 2.1 publications/year), per billion US dollars GDP (0.85 ± 0.21 publications/year) and per 1000 Medline publications (15 ± 4 publications/year). Europe was the most productive world region in absolute numbers (54%) and Australia/New Zealand in relative numbers per million inhabitants and per 1000 billion US dollars GDP. Almost 87% of all publications in HR and F&S came from the 18 countries with a GDP per capita of >10 000 US dollars. In conclusion, the geographical distribution of publications in HR and F&S follows the pattern of the distribution of publications in general biomedical research. Most publications come from affluent countries. Although the USA and the UK appear to be the most productive countries in absolute numbers, smaller affluent countries like Israel and Belgium are more productive when the numbers are normalized to population or GDP.

Key words: fertility/geography/internet/Medline/reproductive medicine

Introduction

Reproductive medicine is a young and increasingly productive field in biomedical research. Research productivity in general may vary widely between different states or countries (Benzer et al., 1993Go). The number of biomedical publications in the USA was evaluated and it was shown that although highly populous states have high numbers of publications, smaller states can also be productive (Thompson, 1999Go). When the normalized number of biomedical publications in the European Union was compared, the Northern countries, the Netherlands and Spain were shown to be most productive (Hefler et al., 1999Go).

Curious about the productivity of research in reproductive medicine in individual countries, we compared the number of publications in the two leading journals of this field [Human Reproduction (HR) and Fertility and Sterility (F&S)], normalized to population size and gross domestic product (GDP).

Materials and methods

The Medline database was searched in October 1999, according to the method recently described (Thompson et al., 1999), using the internet provider PubMed (http://www.ncbi.nlm.nih.gov/PubMed/medline.html). Firstly the advanced-search option was selected and `Human Reproduction' or `Fertility and Sterility' was entered in the `journal name' field. Secondly the name of the country was typed in the `affiliation' field. Following this search strategy, all kinds of papers were counted. The list of the 83 countries was based on the list of members of the European Society of Human Reproduction and Embryology (ESHRE, 1997Go) and on the list of members of the International Federation of Fertility Societies (IFFS) (http://www.mnet.fr/iffs/a_memb.htm). To prevent false-positive results, the words `but not' were added to the search-string (e.g. Ireland but not Northern). To prevent false-negative results in the USA, the names of the 50 states were added, using the word `or' in the search-string. In the same way Scotland, Northern Ireland, Wales and England were added to the name UK. Alternative names for a country were added using the word `or' in the search string (e.g. UK `or' United Kingdom). Thirdly the year of publication was entered in the `publication date' field. The first and last year of search were 1990 and 1999 respectively.

The numbers of publications from each country and each year were collected in a spreadsheet. The countries were classified in seven world regions, based on the classification of the World Health Organization (WHO) (http://www.who.org/whr/1999/en/report.htm). The data were analysed and normalized to population size, GDP and total number of Medline publications in the 1990s. The population size and GDP of each country were obtained from the World Health Report 1999, published on the web-site of the WHO (http://www.who.org/whr/1999/en/report.htm).

Results

The total number of publications in HR and F&S in the 1990s was 9722. Following the described method, we were able to identify the affiliation of 8511 publications (88%). These 8511 publications came from 56 countries. Twenty-seven countries had no publications at all. The 4630 publications of HR came from 46 countries and the 3881 publications of F&S came from 42 countries. The total number of Medline publications of the 56 countries with publications in HR or F&S was 2.475x106. The overall number of publications in HR and F&S per 1000 Medline publications was 3.4 [95% confidence interval (CI): 3.3–3.5].

The lists of the 10 most productive countries and their absolute numbers of publications are shown in Table IAGo, B and C. The UK was the most productive country in HR (21%), and the USA was the most productive country in F&S (45%) and in both journals together (28%). The 10 most productive countries mentioned in Table ICGo were responsible for 79% of all publications in HR and F&S.


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Table I. Top 10 countries according to the number of Human Reproduction and Fertility and Sterility publications between 1990 and 1999 per year (mean ± SD): absolute numbers (AC) and relative numbers representing both journals (DF)
 
The normalized numbers of publications are shown in Table ID, E and FGo. Looking at the number of publications per million inhabitants (Table IDGo), Israel was the most productive country, followed by Belgium. Highly populous countries such as USA and Japan were not represented in this top 10. Almost the same pattern was seen in Table IEGo, which shows the number of publications per billion US dollars GDP. Table IFGo shows the number of publications in HR and F&S per 1000 Medline publications from the respective countries. Again Israel (and Belgium) were the leading countries in this top 10, which also contained countries with a low absolute number of publications like Indonesia.

The absolute and relative numbers of publications in seven world regions are shown in Table IIGo. Europe was responsible for 68% of the HR publications, and North America was responsible for 50% of the F&S publications. These two regions together were responsible for 86% of all publications in both journals. Australia/New Zealand was the most productive region per million inhabitants and per 1000 billion US dollars GDP. Eastern Mediterranean, Australia/New Zealand and Europe were the regions with the highest number of publications in HR and F&S per 1000 Medline publications from the respective regions. These regions scored significantly higher than all regions together (6.4, 5.4 and 5.0 respectively versus 3.4 (95% CI: 3.3–3.5). The remaining regions, including North America, scored significantly lower.


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Table II. Number of Human Reproduction and Fertility and Sterility publications in seven world regions between 1990 and 1999 per year (mean ± SD)
 
Figure 1Go shows the number of publications per year as a function of the GDP per capita. There appeared to be a threshold of 10 000 US dollars. If people in a country earned less than this threshold, the number of publications was relatively low (below six publications per year). The 18 countries with a GDP per capita of more than 10 000 US dollars were responsible for 87% of all publications in HR and F&S. Considering the total number of Medline publications as a function of the GDP per capita, a similar pattern was seen, with again a threshold of 10 000 US dollars (data not shown). The 18 countries with a GDP per capita of more than 10 000 US dollars were responsible for 90% of all Medline publications.



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Figure 1. The mean number of Human Reproduction and Fertility and Sterility publications between 1990 and 1999 per year of different countries, as a function of the gross domestic product (GDP) in US dollars per capita in that country.

 
Figure 2Go shows the ratio between the number of publications in HR and/or F&S in the last 5 years of the 1990s and the number of publications in HR and/or F&S in the first 5 years of the 1990s. Overall, the number of publications in HR increased (ratio 1.9) and the number of publications in F&S remained constant (ratio 1.0). Growth regions for HR were North America (ratio 2.6), South-East Asia (ratio 2.4) and Eastern Mediterranean (ratio 2.4).



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Figure 2. Ratio between the number of Human Reproduction and Fertility and Sterility publications in the second half of the 1990s (1995–1999), and the number of publications in the first half of the 1990s (1990–1994) in seven world regions. The base line represents a ratio of 1 (= no increase or decrease in the number of publications).

 
Discussion

This is the first study to investigate the geographical distribution of publications in reproductive medicine. The affluent and highly populous USA appeared to be the most productive country in the two leading journals in reproductive medicine. However, when normalized to population size and GDP, smaller affluent countries, such as Israel and Belgium, were more productive.

We realize that our method has limitations and biases. Simple counts of the number of publications are only crude estimates of the research output of a country and do not necessarily reflect the quality or clinical relevance of the papers. However, counting publications is at present the only practical way to compare research productivity between different countries. To avoid counting publications with very different impact factors, we chose to count the publications in the two main journals covering reproductive medicine with the highest impact factors (HR and F&S). This choice may be disadvantageous for countries that prefer publication in their own language in local journals. One should also take into account that we only counted the affiliation of the corresponding author, not the affiliation of other authors. Furthermore, we normalized the number of publications to population size and GDP. As has been suggested earlier (Takei, 1999Go), adjustment for the nation's budget for biomedical research would be a better correction factor than the GDP, but this figure was not available for most countries. Finally, there is the problem of false-positive and false-negative results. We have tried to avoid this problem by adding names to the search string using the words `but not' and `or'. Assuming a relatively low number of false-positive results, the false-negative problem cannot be large, since the affiliation could be detected in 88% of all publications.

With respect to the absolute number of publications, the USA and the UK were most productive. These two countries together were responsible for 42% of all publications (Table ICGo). Both countries are affluent, relatively highly populous and are very active in general medical research. Moreover, researchers from these countries have the advantage that they can publish in their own language.

However, after normalization of the data to population size or GDP, Israel, Belgium and other less populous but affluent countries were most productive. The relatively high position of Belgium may be explained by the fact that intracytoplasmic sperm injection (ICSI) was developed in this country and by the fact that the ESHRE office is situated in Belgium. The undisputed high position of Israel is remarkable. It is a small affluent country with probably a relative preference for publishing papers on reproductive medicine. According to Table IFGo, other countries, such as Indonesia and Egypt, also appeared to have a preference for publishing papers on reproductive medicine, but this finding is only of limited value because of the low absolute numbers. Moreover, it is not clear whether these figures mean that a country has more papers in reproductive medicine or fewer in other fields.

Our observation that highly populous affluent countries may be very productive in absolute numbers of publications in reproductive medicine and that less populous affluent countries may be very productive in relative numbers is in agreement with earlier studies of output of biomedical research in general, since comparable patterns were found in studies of the output of biomedical research in the whole world (Benzer et al., 1993Go), in the European Union (Hefler et al., 1999Go) and in the USA (Thompson, 1999Go). Hence, the geography of publications in reproductive medicine follows the geographical pattern of publications in biomedical research in general.

Looking at the absolute number of publications per world region, it can be seen that the majority of all publications were from Europe or North America. If the data are normalized to population or GDP, the less populous but affluent region of Australia and New Zealand was the most productive one. The absolute productivity and relative productivity of Africa, Latin America and Eastern Mediterranean were remarkably low. This is not specific for reproductive medicine, since the numbers of publications in HR and F&S per 1000 Medline publications from these regions were equal to or even higher than from North America.

Considering the numbers of publications in HR and F&S per 1000 Medline publications, the low relative output of North America and the high relative output of Europe and Australia/New Zealand are remarkable.

Looking at the number of publications as a function of GDP per capita, it is obvious that there appears to be a threshold of 10 000 US dollars. If the GDP per capita is lower, the productivity is very low. If the GDP per capita is above this threshold, the productivity increases. Almost 90% of all publications were from affluent countries with a GDP per capita of at least 10 000 US dollars. Again this finding was not specific for reproductive medicine. The same threshold was found when looking at the number of all Medline publications as a function of GDP per capita.

The ratios shown in Figure 2Go provide an indication of the increase of publications in the 1990s. Obviously not all 1999 publications were known in October 1999, so the real increase will be higher. The finding that the number of publications per year is increasing in HR and remains constant in F&S may be due to the fact that HR has had a slightly higher impact factor than F&S during the last few years. In addition, different policies of the editors may play a role. HR is the journal of ESHRE, a relatively young and growing society. The growth regions for its journal (North America, South-East Asia and Eastern Mediterranean) are apparently outside Europe.

In conclusion, the geographical distribution of publications in the two leading journals in reproductive medicine follows more or less the pattern of the geographical distribution of publications in biomedical research in general. Most publications arise from affluent countries with a GDP per capita of >10 000 US dollars. Although the USA appeared to be the most productive country in reproductive medicine in absolute numbers, smaller affluent countries, like Israel and Belgium, were more productive when the numbers were normalized to population or GDP.

Notes

3 To whom correspondence should be addressed at: Department of Gynaecology and Obstetrics, University Hospital Nijmegen, PO Box 9101, 6500 HB Nijmegen, The Netherlands.E-mail: j.kremer{at}obgyn.azn.nl Back

* Presented in part at the 16th Annual Meeting of ESHRE, Bologna, June 25–28, 2000. Back

** J.L.H.Evers is member of the Editorial Board of Human Reproduction. Back

References

Benzer, A., Pomaroli, A., Hauffe, H. and Schmutzhard, E. (1993) Geographical analysis of medical publications in 1990. Lancet, 341, 247.[ISI][Medline]

Hefler, L., Tempfer, C. and Kainz, C. (1999) Geography of biomedical publications in the European Union, 1990–98. Lancet, 353, 1856.[ISI][Medline]

ESHRE (1997) Membership directory. Focus on reproduction 4/97, p. 1.

Takei, N. (1999) Geography of medical publications. Lancet, 354, 516–517.

Thompson, D.F. (1999) Geography of US biomedical publications, 1990 to 1997. N. Engl. J. Med., 340, 817–818.[Free Full Text]





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