ex2117: Effect of Stress During Conception on Odds of a Male Birth
Description
The probability of a male birth in humans is about .51. It has
previously been noticed that lower proportions of male births are
observed when offspring is conceived at times of exposure to smog,
floods or earthquakes. Danish researchers hypothesised that sources
of stress associated with severe life events may also have some
bearing on the sex ratio. To investigate this theory they obtained
the sexes of all 3,072 children who were born in Denmark between 1
January 1980 and 31 December 1992 to women who experienced the
following kind of severe life events in the year of the birth or the
year prior to the birth: death or admission to hospital for cancer or
heart attack of their partner or of their other children. They also
obtained sexes on a sample of 20,337 births to mothers who did not
experience these life stress episodes. This data frame contains the
data that were collected. Noticed that for one group the exposure is
listed as taking place during the first trimester of pregnancy. The
rationale for this is that the stress associated with the cancer or
heart attack of a family member may well have started before the
recorded time of death or hospital admission.encoding
latin1source
Ramsey, F.L. and Schafer, D.W. (2013). The Statistical Sleuth: A
Course in Methods of Data Analysis (3rd ed), Cengage Learning.References
Hansen, D., M�ller, H. and Olsen, J. (1999). Severe
Periconceptional Life Events and the Sex Ratio in Offspring: Follow Up
Study based on Five National Registers, British Medical Journal
319(7209): 548--549.