Supporting pregnant women to make informed choices about Down syndrome screening is widely endorsed. We reviewed the literature on: (a) the association between socioeconomic position and informed choices and decision-making about Down syndrome screening, and (b) the possible mediating variables (e.g., health literacy, numeracy skills, behavioral and communication variables) that might explain the relationship. EMBASE, MEDLINE, PubMed, CINAHL, and PsycINFO were searched from January 1999 to September 2014. The methodological quality of studies was determined by predefined criteria regarding the research aims, study design, study population and setting, measurement tools, and statistical analysis. A total of 33 studies met the inclusion criteria. Women from lower socioeconomic groups experience greater difficulties making informed choices about Down syndrome screening compared to women from higher socioeconomic groups. Most studies focus on individual dimensions of informed decision-making rather than assessing elements in conjunction with one another. Few studies have explored why there are socioeconomic differences in women's ability to make informed screening decisions. Future work is needed to identify mediating variables in this pathway. Systematic evidence-based intervention development to improve communication, understanding, and decision-making about Down syndrome screening is needed to ensure that women have an equal opportunity to make an informed choice about screening regardless of their socioeconomic position.