Sex ratio at birth for urban and rural areas.

Previous studies show that sex ratio at birth in China's urban areas is usually higher than that of rural areas. The higher proportion of 1st births in urban areas was once taken to explain the cause for the higher sex ratio. The data of the 1982 fertility sampling survey show that the sex ratio at birth during the period from 1964 to 1981 remains higher in the urban areas (108.0) than in the rural areas (107.8). Further studies are yet needed on the differentials in sex ratios at birth between urban and rural areas and on their causes. The sex ratio in 1981 of the 29 provinces, municipalities and autonomous regions in China's mainland was 108.5, somewhat higher than that of most countries in the world. 2 things account for the occurrence. 1 is that, biologically, certain particularities may exist in the sex ratio at birth of China's population, for the ratio varies with ethnic groups, nationalities and regions. The other is that, sociologically, female infants may be underreported in some areas and the phenomenon of infanticide left over by history still exists in some isolated cases. These surveys suggest that a certain specific characteristic does exist in the sex ratio at birth of China's urban areas, but they also contribute to the explanation of the higher sex ratio at birth of the total population of the country.