The geography of the age at menopause in central Portugal since the early twentieth century

Abstract

This work aims at studying the spatio-temporal evolution of the age at menopause in central Portugal since the early twentieth century. We analyzed $$N=320,444$$ N = 320 , 444 women that had already reached the menopause within a free breast cancer screening program between 1990 and 2018 and born in the period 1910–1960. One of the concerns was about early or late menopause thus we considered percentile regression to build the respective percentile curves inside the package GAMLSS in R. In order to capture the correlation at the regional level, a spatial random-effect was considered. The obtained clustered spatial effects were analyzed to assess geographical differences among the percentiles of the age at menopause by year of birth. An increasing trend in the median age at menopause and regional differences for all the considered percentiles were found. From 47.1 years in 1910 to 49.59 years in 1960 (about 2.49 years in 5 decades). Early and premature menopause (below percentile 5%) occur in the interior north (north-eastern). Late menopause (above percentile 95%) occur predominantly in the central-north and central-south areas.