Abstract

Birthweight and its different classifications are related to different health problems later in life. Although the underlying mechanisms affecting birthweight are not well understood, one of the most interesting social factors affecting birthweight is age at maternity, although it is not possible to analyse age at maternity without analysing both level of education of the mother and the maternal occupation. In the last decades, age at maternity has increased in developed countries, increasing the number of mothers who are older than 35 years old and older than 40 years old, with a parallel increase of mothers who are highly educated and with high-income occupations. The delay of age at maternity is demonstrated to increase the prevalence of negative pregnancy outcomes as low birthweight (LBW) or small for gestational age (SGA), and is related to higher number of pregnancies by assisted reproductive technology (ART), fact that could partly explain higher number of multiple births. Nevertheless, higher-income occupation and higher level of education are related to better pregnancy outcomes. A simple directed acyclic graph is drawn to give an example of the possible relationships among age at maternity, multiple birth, and assisted reproductive technology and pregnancy outcomes.

Keywords: Age at maternity; Multiple birth; Birthweight; Small for gestational age; Large for gestational age; Low birthweight; Assisted reproductive technology