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EDITORIALS: Jens Peter Ellekilde Bonde and Allen Wilcox Ratio of boys to girls at birth BMJ 2007; 334: 486-487 [Full text]

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other factors affecting the ratio

Sebastian Kraemer   (11 March 2007)

other factors affecting the ratio 11 March 2007
Sebastian Kraemer, Consultant Child and Adolescent Psychiatrist Whittington Hospital, London N19 5NF Send response to journal: Re: other factors affecting the ratio	The fact that the ratio of boys to girls at birth falls following periconceptual catastrophe is an indication of a powerful stress effect. Smaller stresses will surely have smaller effects but all will have an impact on the ratio. Hanson D, Møller H, Olsen J. Severe peri-conceptional life events and the sex ratio in offspring: follow up study based on five national registers. BMJ 1999; 319: 548-549 Catalano R, Bruckner T, Marks AR, Eskenazi B. Exogenous shocks to the human sex ratio: the case of September 11, 2001 in New York City, Human Reproduction 2006 21(12):3127-3131 Competing interests: None declared