English to Spanish Social Sciences International Org/Dev/Coop Statistics

One of the main demographic changes occurring in the world is the decline of fertility. However, to a considerable extent this decline has occurred on account of the reduction of ***higher order births, to older women;*** adolescent fertility is declining slowly or even rising in some countries.
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¡Hola!
Necesito el término que se usa en estadísticas, por favor. Encontré "nacimientos de orden superior", pero bien podría tratarse de malas traducciones ;-)
Muchas gracias de antemano por su ayuda.