Analysis of the spatial patterns of consanguinity and its association with late childbearing in Sardinia using advanced GIS methods

The current Western tendency to postpone childbearing is widely studied for its onerous personal and socio-economic cost in reproductive outcome and progeny health. Such behaviour is particularly alarming in those populations, like the Italian one, characterized by extremely low fertility rates. We show how advanced GIS techniques can be used to identify regions where mothers succeed in late reproduction, and to investigate the role of possible biological determinants. Through spatial analysis we explored consanguinity in Sardinia and its association with late childbearing, using 1930-1969 data regarding consanguineous marriages and fertility of contemporaneous women. We identified a Central-Eastern zone where, despite the expected negative impact of inbreeding on fertility, such positive association exists and does not significantly change the incidence of highly fertile mothers, by that suggesting that genetic determinants, enhanced in homozygous association, can affect late fertility. Since this area includes the Ogliastra region, widely studied for its genetic homogeneity, and largely overlaps the well known 'Blue Zone' of extreme longevity, its population qualifies for further deeper investigations on possible common biological, genetic and environmental determinants