In a study around 2002, the natural sex ratio at birth was estimated to be within a narrow range of 1.07 to 1.03 males/female.[4][9] Some scholars suggest that countries considered to have significant practices of prenatal sex-selection are those with birth sex ratios of 1.08 and above (selection against females) and 1.02 and below (selection against males). This assumption has been questioned by some scholars.[2]