Decline in sex ratio at birth after Kobe earthquake

Abstract

We investigated the possible association between the Kobe earthquake (January 1995) and the sex ratio among live-born infants after the catastrophe. A significant decline in the sex ratio (0.501) of Hyogo Prefecture in October 1995 was observed 9 months after the Kobe earthquake as compared with an expected value of 0.516 in the period from January 1993 to January 1996 (P = 0.04; one-tailed). Simultaneously, a reduction in fertility of approximately 6% was also observed, compared with the month of October 2 years previously. Thus, the acute stress resulting from a great natural catastrophe can be a cause of a low sex ratio at birth 9 months later.

The Influence of Migration on Secular Trends in Sex Ratios at Birth in Cuba in the Past Fifty Years

“…In accordance with this hypothesis, M/F wanes when adverse environmental factors are present. It has been shown, for example, that M/F declines after traumatic events such as earthquakes (11) and other environmental disasters (12). This is because such events appear to encourage stressed females to spontaneously abort male foetuses in excess of female foetuses (13) in accordance with the Trivers-Willard hypothesis (10).…”

Civil conflict, gender-specific fetal loss, and selection: A new test of the Trivers–Willard hypothesis

“…4 See Lazarus (2002) and Fukuda et al (1998) for discussions on the determination of the sex-ratio at conception. after birth.…”

“…Such a phenomenon has been recorded in a range of circumstances, including earthquakes (Fukuda et al (1998), Torche & Kleinhaus (2012)), terrorist attacks , unusually cold years (Catalano et al 2008), pollution exposure (Sanders & Stoecker 2011), and maternal fasting (Almond & Mazumder 2011). Lack of data on pregnancies not ending in a live birth has prevented previous studies from investigating directly the impact of adverse shocks on fetal loss.…”

“…Some information on fetal loss can be obtained indirectly through the timing of exposure. If exposure during the first month is found to matter (as in Fukuda et al (1998) and Almond & Mazumder (2011)), then it is not clear whether the effect on the sex ratio at birth is due to an effect on the sex ratio at conception or due to genderdifferentiated rates of miscarriage.…”

Relationship between the Noto-Peninsula earthquake and maternal postnatal depression and child-rearing

“…Of these, few have examined the effects of disaster-related stress on perinatal women [6][7][8][9]. The findings of these earlier studies suggest that prenatal stress caused by natural and man-made disasters may result in minor psychiatric distress [3,4], low birth weight [7], preterm delivery [6,10], smaller head circumference [6,7], skewed sex ratios [9], retardation of fetal brain development [11], and reduction of breast milk supply [8]. It also would seem that pregnant women are more susceptible to the effects of stress in the first trimester than in the second and third trimesters [6,10,12].…”