• Data reference period
• Place of residence (NUTS - 2024)

• RESIDENT POPULATION:  Set of persons who, regardless of being present or absent in a given housing unit at the moment of observation, have lived in the place of their usual residence for a continuous period of 12 months prior to the moment of observation, or have arrived to the place of their usual residence during the period of 12 months prior to the moment of observation, with the purpose of living there for a year, at least.
• GENERAL FERTILITY RATE:  The ratio of the number of live births during a given period, usually a calendar year, to the average women of child-bearing age (aged 15 to 49) in that period (usually expressed as the number of live births per 1000 (10^3) women of child-bearing age).
• REFERENCE PERIOD:  Period to which the information refers and which may be a specific day or a time interval (month, fiscal year, calendar year, among others).

`[(sum_(i=15)^(i=49)(f i,t x (i+0,5)))] /(sum_(i=15)^(i=49)(f i,t)) `

         Being i the age of the woman at the birth of the child; t the reference calendar year and fit the fertility rate at age i at time t.