ABSTRACT
We analysed geographic variation in the number of males per 100 females at birth also called the secondary sex ratio (SR), the crude birth rate (CBR), the total fertility rate (TFR) and the twinning rate (TWR). Earlier studies have noted geographic variations in the TWR and racial differences in the SR. Statistical analyses have shown that comparisons between SRs demand large data sets because random fluctuations in moderate data are marked. Consequently, reliable results presuppose national birth data. In this study, we analysed historical demographic data and investigated the geographic variations between the counties in Sweden for the SR among the live born (1749-1869), the CBR in 1751-1870, the TFR in 1860 and the TWR in 1751-1860. We built spatial models and as regressors we used geographic co-ordinates for the residences of the counties in Sweden. The influence of the CBR and TFR on the SR and TWR was examined. For all variables, we obtained spatial variations, albeit of different patterns and power. Hence, no common spatial pattern for the demographic variables SR, TFR, CBR and TWR was detected, but a better fit was noted for TFR, CBR and TWR than for SR.
ABSTRACT
Aims: Interest in the distribution of birth weight arises because of the association between birth weight and the future health of the child. A common statistical result is that the birth weight distribution differs slightly from the Gaussian distribution. Methods: A standard attempt has been done to split the distribution into two components, a predominant Gaussian distribution and an unspecified “residual” distribution. Results: We considered birth weight data among triplets born in Finland in 1905-1959 and compare the birth weight among stillborn and live-born triplets. The stillbirth rates are 119.1 per 1000 births for males, 124.6 for females and 121.8 for all. The sex differences are not significant. The still birth rate for the period 1905-1930 was 119.5 and for the period 1931-1959, 124.2. We identified a strong association between birth weight of the triplets and their survival. The weight distribution for male triplets is described well by the Gaussian curve, while for females a slight deviation from the Gaussian distribution is discernible.