engleski

Factors affecting sex ratio at birth in Croatia 1998 – 2008

This investigation aimed to contribute to the existing literature on demographic and ecological factors affecting the sex ratio at birth, analyzing the births in Croatia from 1998 to 2008. Data from birth certificates of all Croatian births for the investigated period (n=420 256) were used to establish the link between parental ages, birth order, region of birth, parental occupation and parental education level, and sex of the child. The Chi square test and t-test were used to assess the significance of each of the factors along with the multiple logistic regression to control for the possible confounding effects. The results suggest that a joint higher age of both parents significantly lowers the sex ratio at birth. There is also a regional variation in sex ratio at birth, the lowest value being in Central Croatia, while the highest is in the City of Zagreb. The changes in the reproductive physiology of older parents are most probably responsible for the lower sex ratio although the limited sample size warns against rapid generalizations. The causes of the regional variation in sex ratio at birth are most likely the different regional levels of obesity and physical inactivity.

sex ratio/Croatia/logistic regression/parental age/obesity

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