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The reported sex ratio at birth is the number of male births per 100 female births enumerated in a census, a survey, or civil registration. Theoretically, the reported sex ratio should be equal to the “true” sex ratio (ie, the number of males per 100 females born in a population), which is biologically stable around the value of 106 in the absence of social and behavioral interference. Yet, by using survey and census data, many studies have identified discrepancies between true and reported sex ratios at birth in most countries, especially in the developing world. Three main proximate causes of this “imbalance” of reported sex ratios at birth have generally been identified: female infanticide, underreporting of girls, and sexselective abortion practices. 1 Important distant causes of abnormally high sex ratios at birth are usually acknowledged to be the implementation of family planning policies targeted at fertility reduction and …