This study examined the associations between maternal perinatal mental health or exposure to long-chain polyunsaturated fatty acids (LCPUFAs) in relation to infant development in the Pregnancy, Infection, and Nutrition Study (2002-2006) (n=358). Certain LCPUFAs have been shown to benefit visual acuity, while maternal mental health may negatively affect child development. Women completed questionnaires during pregnancy to assess trait anxiety and depressive symptoms. A home visit in the fourth postpartum month assessed perceived stress and depressive symptoms, collected infant feeding data, and obtained breast milk samples. Infant development was assessed at 12 months using the Mullen Scales of Early Learning. Multivariable linear regression was used to examine the associations between trait anxiety, perceived stress, and depressive symptoms in relation to Mullen scores. Similar techniques were used to examine LCPUFA exposure in relation to Mullen scores and whether women with elevated depressive symptoms had lower breast milk docosahexaenoic acid (DHA) concentration. High levels of trait anxiety were associated with lower Receptive Language (adjusted [beta]=-2.9, 95% confidence interval: -5.6, -0.3) and Early Learning Composite (adjusted [beta] =-4.5, CI: -8.9, 0.0) scores. No associations were observed between anxiety and other sub-scale scores or between perceived stress or depressive symptoms and Mullen scores. Mean DHA content of breast milk samples was 0.28% of fatty acids (standard deviation=0.22); mean arachidonic acid (AA) content 0.57% (SD=0.20). Women with elevated depressive symptoms before 20 weeks gestation had 25% lower breast milk DHA than women with few symptoms. Upon adjustment for preterm birth, smoking, race and ethnicity, and education, no differences in development were observed in relation to breastfeeding exclusivity. No association was observed between the LCPUFA content of breast milk and formula and development. Maternal anxiety may influence overall infant cognitive development and the ability to process verbal input. Women who experienced elevated depressive symptoms in early pregnancy may have less DHA available to their infants. However, this study found no evidence of enhanced development related to LCPUFAs. Given the conflicting results among previous studies and this study's limitations, no actions are currently warranted to change infant feeding practices except to note that infant LCPUFA supplementation deserves further study
