Population loss has made demographic structures in the area quite unbalanced in terms of aging, and Peñamellera Baja now has a relatively high median age for the region. The same is not true for the sex ratio; Peñamellera Baja presents one of the most equal sex ratios in the whole region of the Picos de Europa. Currently, the majority of the population is concentrated around the Deva River in the north of the municipality, while the southern part is quite depopulated except for the parishes of San Esteban and Cuñaba.