RT Journal Article
SR Electronic
T1 Association between sexes of successive siblings in data from Demographic and Health Survey program
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 031344
DO 10.1101/031344
A1 Mikhail Monakhov
YR 2015
UL http://biorxiv.org/content/early/2015/11/12/031344.abstract
AB Prediction of future child’s sex is a question of keen public interest. Probability of having a child of either sex is close to 50%, although multiple factors may slightly change this value. Some demographic studies suggested that sex determination can be influenced by previous pregnancies, although this hypothesis was not commonly accepted. This paper explores correlations between siblings’ sexes using data from Demographic and Health Survey program. In the sample of about 2,214,601 women (7,985,855 children), frequencies of offsprings with multiple siblings of same sex were significantly higher than can be expected by chance. Logistic regression analysis suggested that these deviations of frequencies were driven by positive correlation between sexes of successive siblings (coefficient = 0.065, p < 0.001). This correlation could be caused by secondary sex ratio adjustment in utero since the effect was decreasing with length of birth-to-birth interval, and birth-to-birth interval was longer for siblings with unlike sex.