Declines in Sex Ratio at Birth and Fetal Deaths in Japan and U.S. Whites
Author Information
Author(s): Davis Devra Lee, Webster Pamela, Stainthorpe Hillary, Chilton Janice, Jones Lovell, Doi Rikuo
Primary Institution: Center for Environmental Oncology, University of Pittsburgh Cancer Institute
Hypothesis
What factors are contributing to the decline in sex ratio at birth and fetal deaths in Japan and U.S. whites, but not in African Americans?
Conclusion
The study found significant declines in sex ratios at birth for U.S. whites and Japan, but not for African Americans, indicating unexplained trends in these populations.
Supporting Evidence
- Sex ratio at birth has declined significantly in Japan and in U.S. whites.
- The male proportion of fetal death has increased overall in Japan and the United States.
- Known risk factors cannot fully explain the recent trends in sex ratios.
- Fetal death rates in Japan are typically more than twice those of the United States.
- Improvements in obstetric care may affect sex ratios differently across racial groups.
Takeaway
In Japan and among white Americans, fewer boys are being born compared to girls, while this trend is not seen in African Americans.
Methodology
Public health records from national statistical agencies were analyzed to assess trends in sex ratio at birth and fetal deaths from 1970 to 2002 in the U.S. and from 1970 to 1999 in Japan.
Potential Biases
Potential biases in data collection and reporting of sex at birth and fetal deaths may exist.
Limitations
The study does not fully account for all known and hypothesized risk factors for reduced sex ratios.
Participant Demographics
The study focused on U.S. whites, African Americans, and the population of Japan.
Statistical Information
P-Value
p < 0.001
Statistical Significance
p < 0.01
Digital Object Identifier (DOI)
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