DEFINITION: The number of males for each female one of five age groups - at birth, under 15 years, 15-64 years, 65 years and over, and for the total population. Sex ratio at birth has recently emerged as an indicator of certain kinds of sex discrimination in some countries. For instance, high sex ratios at birth in some Asian countries are now attributed to sex-selective abortion and infanticide due to a strong preference for sons. This will affect future marriage patterns and fertility patterns. Eventually it could cause unrest among young adult males who are unable to find partners.