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Declines in Sex Ratio at Birth and Fetal Deaths in Japan, and in U.S. Whites but Not African Americans

BACKGROUND: The expected ratio of male to female births is generally believed to be 1.05, also described as the male proportion of 0.515. OBJECTIVES: We describe trends in sex ratio at birth and in fetal deaths in the United States, in African Americans and in whites, and in Japan, two industrial co...

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Autores principales: Davis, Devra Lee, Webster, Pamela, Stainthorpe, Hillary, Chilton, Janice, Jones, Lovell, Doi, Rikuo
Formato: Texto
Lenguaje:English
Publicado: National Institute of Environmental Health Sciences 2007
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1892130/
https://www.ncbi.nlm.nih.gov/pubmed/17589604
http://dx.doi.org/10.1289/ehp.9540
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author Davis, Devra Lee
Webster, Pamela
Stainthorpe, Hillary
Chilton, Janice
Jones, Lovell
Doi, Rikuo
author_facet Davis, Devra Lee
Webster, Pamela
Stainthorpe, Hillary
Chilton, Janice
Jones, Lovell
Doi, Rikuo
author_sort Davis, Devra Lee
collection PubMed
description BACKGROUND: The expected ratio of male to female births is generally believed to be 1.05, also described as the male proportion of 0.515. OBJECTIVES: We describe trends in sex ratio at birth and in fetal deaths in the United States, in African Americans and in whites, and in Japan, two industrial countries with well-characterized health data infrastructures, and we speculate about possible explanations. METHODS: Public health records from national statistical agencies were assembled to create information on sex ratio at birth and in fetal deaths in the United States (1970–2002) and Japan (1970–1999), using SPSS. RESULTS: Sex ratio at birth has declined significantly in Japan and in U.S. whites, but not for African Americans, for whom sex ratio remains significantly lower than that of whites. The male proportion of fetal death has increased overall in Japan and in the United States. CONCLUSIONS: Sex ratio declines are equivalent to a shift from male to female births of 135,000 white males in the United States and 127,000 males in Japan. Known and hypothesized risk factors for reduced sex ratio at birth and in fetal deaths cannot account fully for recent trends or racial or national differences. Whether avoidable environmental or other factors—such as widespread exposure to metalloestrogens or other known or suspected endocrine-disrupting materials, changes in parental age, obesity, assisted reproduction, or nutrition—may account for some of these patterns is a matter that merits serious concern.
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spelling pubmed-18921302007-06-22 Declines in Sex Ratio at Birth and Fetal Deaths in Japan, and in U.S. Whites but Not African Americans Davis, Devra Lee Webster, Pamela Stainthorpe, Hillary Chilton, Janice Jones, Lovell Doi, Rikuo Environ Health Perspect Research BACKGROUND: The expected ratio of male to female births is generally believed to be 1.05, also described as the male proportion of 0.515. OBJECTIVES: We describe trends in sex ratio at birth and in fetal deaths in the United States, in African Americans and in whites, and in Japan, two industrial countries with well-characterized health data infrastructures, and we speculate about possible explanations. METHODS: Public health records from national statistical agencies were assembled to create information on sex ratio at birth and in fetal deaths in the United States (1970–2002) and Japan (1970–1999), using SPSS. RESULTS: Sex ratio at birth has declined significantly in Japan and in U.S. whites, but not for African Americans, for whom sex ratio remains significantly lower than that of whites. The male proportion of fetal death has increased overall in Japan and in the United States. CONCLUSIONS: Sex ratio declines are equivalent to a shift from male to female births of 135,000 white males in the United States and 127,000 males in Japan. Known and hypothesized risk factors for reduced sex ratio at birth and in fetal deaths cannot account fully for recent trends or racial or national differences. Whether avoidable environmental or other factors—such as widespread exposure to metalloestrogens or other known or suspected endocrine-disrupting materials, changes in parental age, obesity, assisted reproduction, or nutrition—may account for some of these patterns is a matter that merits serious concern. National Institute of Environmental Health Sciences 2007-06 2007-04-09 /pmc/articles/PMC1892130/ /pubmed/17589604 http://dx.doi.org/10.1289/ehp.9540 Text en http://creativecommons.org/publicdomain/mark/1.0/ Publication of EHP lies in the public domain and is therefore without copyright. All text from EHP may be reprinted freely. Use of materials published in EHP should be acknowledged (for example, ?Reproduced with permission from Environmental Health Perspectives?); pertinent reference information should be provided for the article from which the material was reproduced. Articles from EHP, especially the News section, may contain photographs or illustrations copyrighted by other commercial organizations or individuals that may not be used without obtaining prior approval from the holder of the copyright.
spellingShingle Research
Davis, Devra Lee
Webster, Pamela
Stainthorpe, Hillary
Chilton, Janice
Jones, Lovell
Doi, Rikuo
Declines in Sex Ratio at Birth and Fetal Deaths in Japan, and in U.S. Whites but Not African Americans
title Declines in Sex Ratio at Birth and Fetal Deaths in Japan, and in U.S. Whites but Not African Americans
title_full Declines in Sex Ratio at Birth and Fetal Deaths in Japan, and in U.S. Whites but Not African Americans
title_fullStr Declines in Sex Ratio at Birth and Fetal Deaths in Japan, and in U.S. Whites but Not African Americans
title_full_unstemmed Declines in Sex Ratio at Birth and Fetal Deaths in Japan, and in U.S. Whites but Not African Americans
title_short Declines in Sex Ratio at Birth and Fetal Deaths in Japan, and in U.S. Whites but Not African Americans
title_sort declines in sex ratio at birth and fetal deaths in japan, and in u.s. whites but not african americans
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1892130/
https://www.ncbi.nlm.nih.gov/pubmed/17589604
http://dx.doi.org/10.1289/ehp.9540
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