Análisis histórico de la gemelaridad en EspañaDiferencias regionales

Abstract

In comparison to other European countries, research on twinning is scarce in Spain. In general, short periods of time have been studied, and in no case do they consider years previous to 1950. Twinning regional variation as not been extensively studied. The purpose of the present paper is to provide a wider temporal knowledge of twining in Spain throughout the XXth century. Taken into account is the influence of demographic variables such as the crude birth rate and the mean maternity age. Regional variation in twinning rate has also been considered. Using information from the National Statistics Institute from 1900 to 2006, the yearly Spanish twinning rates were calculated, as well as the provincial mean rates for three periods: 1900-9, 1960- 69 and 1980-9. The yearly rates were positively correlated with the average maternal age (1922-1989) and negatively with the birth rate before 1969. Regarding regional differences, a geographic analysis provided categorized graphic representations of the provincial pattern variation in twinning for three separate periods and demographically relevant (1900-9, 1960-69 and 1980-9).