Determinants of dietary patterns and diet quality during pregnancy: a systematic review with narrative synthesis

Objective: To identify determinants of diet in pregnancy, by detecting factors in our multiple-determinants life course framework that are associated with dietary patterns, quality or guideline adherence. Design: A systematic review of observational studies, published in English or German, was conducted. Sociodemographic, lifestyle, environmental and pregnancy-related determinants were considered. Four electronic databases were searched in January 2015 and updated in April 2016 and a total of 4368 articles identified. Risk of bias was assessed using adapted Newcastle-Ottawa Scales. Setting: High- and upper-middle-income countries. Subjects: Pregnant or postpartum women reporting their dietary intake during pregnancy. Results: Seventeen publications of twelve studies were included and compared narratively due to heterogeneity. Diet in pregnancy was patterned along a social gradient and aligned with other health behaviours before and during pregnancy. Few studies investigated the influence of the social and built environment and their findings were inconsistent. Except for parity, pregnancy determinants were rarely assessed even though pregnancy is a physiologically and psychologically unique period. Various less well-researched factors such as the role of ethnicity, pregnancy intendedness, pregnancy ailments and macro-level environment were identified that need to be studied in more detail. Conclusions: The framework was supported by the literature identified, but more research of sound methodology is needed in order to conclusively disentangle the interplay of the different determinants. Practitioners should be aware that pregnant women who are young, have a low education or do not follow general health advice appear to be at higher risk of inadequate dietary intake.