Esto significa que, en unas décadas

Esto significa que, en unas décadas, no habrá suficiente número de personas para sostener el sistema de pensiones, lo que causaría no solamente su desequilibrio, sino su colapso.
Muchas son las razones que explican la baja natalidad y por qué la población en condición reproductiva ha venido retrasando la edad de tener hijos o incluso se ha abstenido de hacerlo, pero los más comunes han sido:
 Los bajos salarios.
 Las altas tasas de desempleo.
 Las escasas oportunidades laborales para la mano de obra de baja cualificación.
 La elevada temporalidad del mercado de trabajo.

Results (English) 1:

This means that, in a few decades, there will be enough people to sustain the pension system, causing not only its imbalance, but its collapse. There are many reasons that explain the low birth rate and why the population in reproductive condition has been delaying the age of having children or even it has refrained from doing so, but the most common are:  low wages. high rates of unemployment. scarce employment opportunities for the low-skilled labor. The high temporality of the labour market.

Results (English) 2:

This means that in a few decades, there will be enough people to sustain the pension system, causing not only the imbalance, but its collapse.
There are many reasons for the low birth rate and why the population of reproductive condition has been delaying childbearing age or has refrained from doing so, but the most common are:
 Low salaries.
 The high unemployment.
 The few employment opportunities for the labor of low qualification.
 The high rate of temporary labor market.

Results (English) 3:

This means that in a few decades, there will not be enough people to maintain the Pension System, which not only cause the imbalance, but its Collapse.Many are the reasons why the Low Birth Rate and the population Reproductive status has been delaying Childbearing age or even has refrained from doing so, but the most common are:To low wages.To the high rates of unemployment.To the limited employment opportunities for Low Skilled Labour.High temporality to the labour market.