Background: Nutritional requirements need to be met in order to adapt to pre- and postnatal changes. Our aim was to systematically review the evidence of associations between nutritional biomarkers and psychological distress during pregnancy and in the first postnatal year.

Methods: MEDLINE, EMBASE, PsycINFO, Scielo, LILACS, clinicaltrials.gov, International Clinical Trials Registry, Cochrane Library, Scopus and Web of Science databases were searched for articles from inception to 4/15/2016. Studies of maternal nutritional biomarkers in blood (fatty acids/micronutrients/amino acids) and associations with psychological distress (depression/anxiety/stress) were included. Two independent reviewers extracted data based on study designs, participants, outcomes, exposures, and association measures.

Results: Thirty-eight studies were included. A total of 13 studies showed divergent or no associations between serum/plasma/erythrocyte fatty acid concentrations and depression/anxiety during pregnancy and postpartum. Changes in serum cholesterol levels from pregnancy to postpartum showed a significant inverse correlation with depression in one out of three studies. Five out of seven studies found an inverse association between serum vitamin D levels and pre- and postnatal depression. Plasma tryptophan levels were inversely correlated with postnatal depression scores in three out of four studies. We identified that one out of two studies presented no significant association between vitamin B₁₂/folate/ferritin concentrations and depression in postpartum.

Limitations: There was higher variability between association measures, time and scales of depression and anxiety assessments.

Conclusions: The majority of high-quality studies suggest that lower vitamin D levels may be associated with postpartum depression. However, further evidence is needed for guiding clinical practice on nutritional biomarkers.