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Trends of Twinning Rates in Ten Countries, 1972-1996

Published online by Cambridge University Press:  01 August 2014

Y. Imaizumi
Y. Imaizumi*
Affiliation:
National Institute of Population and Social Security Research, Ministry of Health and Welfare, Tokyo, Japan
*
National Institute of Populationand Social Security Research, Ministry of Health and Welfare, Kasumigaseki, Chiyoda-ku, Tokyo, Japan; e-mail: imaizumi@so.ipss.go.jp

Abstract

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Trends of twinning rates were analyzed using vital statistics in Austria, Finland, Norway, Sweden, Canada, Australia, Hong Kong, Israel, Japan, and Singapore during the period from 1972 to 1996. The twinning rates increased significantly year by year in each country. During these periods, the twinning rate increased by twenty percent in Austria and Canada, and by sixty percent in Norway and Sweden. The twinning rate was 1.6 times higher in Sweden than in Hong Kong in 1972 and by eighty percent in Israel in 1995. Twinning rates were higher in European countries, Canada, and Australia than in Asia. The variations of the twinning rates among countries were not only due to biological factors, but also to assisted reproductive techniques. In Australia, the overall twinning rate was 1.3 times higher in the nuptial births (14.1 per 1000 births) than in the ex-nuptial births (10.7) during the period 1994-1996. As for maternal age, twinning rates in Sweden increased year by year for maternal age groups except the youngest and the oldest age groups. In Sweden, the rising twinning rate has been attributed to the higher proportion of mothers (for the 25-39 year old age groups) treated with ovulation-inducing hormones and attributed to in-vitro fertilization.

Keywords

Twinning ratesWorld-wideNuptialityMaternal age
Type
Research Article
Information
Acta geneticae medicae et gemellologiae: twin research , Volume 46 , Issue 4 , October 1997 , pp. 209 - 218
Copyright
Copyright © The International Society for Twin Studies 1997

References

REFERENCES

1. Bulmer, MG (1970): The Biology of Twinning in Man. Oxford, England: Clarendon Press.Google Scholar
2. Chen, CJ, Lee, TK, Wang, CJ, Yu, MW (1992): Secular trend and associated factors of twinning in Taiwan. Acta Genet Med Gemellol 41: 205–213.Google Scholar
3. Imaizumi, Y (1992): Twinning rates in Japan, 1951-1990. Acta Genet Med Gemellol 41: 165–175.Google Scholar
4. Imaizumi, Y (1994): Recent and long term trends of multiple birth rates and influencing factors in Japan. J of Epidemiology 4: 103–109.Google Scholar
5. Imaizumi, Y, Nonaka, K (1997): The twinning rates by zygosity in Japan, 1975-1994. Acta Genet Med Gemellol 46: 9–22.Google Scholar
6. Murphy, M, Hey, K, Brown, J, Willis, B, Ellis, JD, Barlow, D (1997): Infertility treatment and multiple birth rates in Britain, 1938-94. J Biosoc Sci 29: 235–243.Google Scholar
7. Pollard, R (1995): Ethnic comparison of twinning rates in California. Human Biology 67: 921–931.Google Scholar
8. Taffel, SM (1992): Health and demographic characteristics of twin births: United States, 1988. Vital and Health Statistics, Series 21, No. 50: 1–17.Google Scholar
9. Westergaard, T, Wohlfahrt, J, Aaby, P, Melbye, M (1997): Population based study of rates of multiple pregnancies in Denmark, 1980-91. BMJ 314: 775–779.Google Scholar
10. Wood, R (1997): Trends in multiple births, 1938-1995. Population Trends, 87 (Spring): 29–35.Google Scholar