Análisis de la evolución histórica de la razón de masculinidad al nacer en España.

This study analyzes sex ratio at birth in Spain from the late 19th century to the present. A detailed examination has been performed for the period between 1975 and 2019, considering over 20 million birth records. In addition to verifying the low reliability of the birth records during the early 20th century, we have also found that, in contrast to general beliefs, this ratio is not consistent. Our data suggest that parental age and race, birth order and intensity of solar radiation, all clearly influence this indicator. [ABSTRACT FROM AUTHOR]