Impact of the 2011 Earthquake on Marriages, Births and the Secondary Sex Ratio in Japan

Bibliographic Data

ID24077097
AuthorsYuri Hamamatsu (0000-0001-7226-330X, The University of Tokyo, corresponding author), Yosuke Inoue (0000-0002-7690-3447, The University of Tokyo), Chiho Watanabe (0000-0002-2114-3903, The University of Tokyo), Masahiro Umezaki (0000-0003-3733-3629, The University of Tokyo)
Year2014
Volume46
Issue6
Pages830-841
Publication date2014-11-01
Peer ReviewedYes
Open AccessYes
TypeARTICLE
VenueJournal of Biosocial Science (JOURNAL)
Journal identifiersISSN: 0021-9320 • E-ISSN: 1469-7599
PublisherCambridge University Press (CUP) (PUBLISHER)
DOI10.1017/s0021932014000017
PMID24503173
OpenAlexW2074669083
LanguageEN
Citations received17
References cited19

On 11th March 2011 a magnitude nine earthquake struck the Tohoku region of Japan. The earthquake resulted in a large tsunami and an accident at the Fukushima Nuclear Power Plant. Previous studies have suggested that demographic indices relating to reproduction and marriage change after such massive disasters (e.g. large earthquakes). The present study investigated whether the number of births, number of marriages and the secondary sex ratio (SSR) changed after the East Japan Earthquake. The monthly number of births (males and females, separately) and marriages in each prefecture in Japan from January 1997 to June 2012 were obtained from the Demographic Survey of Japan. An analysis was performed for three different geographic boundary units: the disaster-stricken area, the non-disaster-stricken area and the whole of Japan. In each unit, the numbers of births and marriages in a given month during the post-disaster period were predicted based on a regression equation estimated by the numbers of births and marriages in that month during the pre-disaster period. The numbers of observed monthly births and marriages during the post-disaster period were compared with the predicted figures. Differences between the observed and predicted numbers were determined by referring to the 95% confidence limits for the predicted mean number. The observed probability of a male birth in a given month during the post-disaster period was compared with a 95% confidence interval of a binominal distribution. In all three boundary units, the number of births was significantly lower than the predicted number by about 3–8% from nine months after the disaster, while the number of marriages in October 2011 was significantly lower than the predicted number by about 25–28%. In October 2011, the SSR in the whole of Japan had decreased from 104.8 (the predicted SSR) to 102.9. The number of births and marriages and the SSR decreased in Japan after the East Japan Earthquake irrespective of locality.

Confidence interval · Geography · Sociology · Statistics · Demographic Trends and Gender Preferences · Demography · Family Dynamics and Relationships · Global Maternal and Child Health · Mathematics