Serum brain-derived neurotrophic factor (BDNF) across pregnancy and postpartum: Associations with race, depressive symptoms, and low birth weight.

BACKGROUND Brain-derived neurotrophic factor (BDNF) is implicated as a causal factor in major depression and is critical to placental development during pregnancy. Longitudinal data on BDNF across the perinatal period are lacking. These data are of interest given the potential implications for maternal mood and fetal growth, particularly among Black women who show ∼2-fold greater risk for delivering low birth weight infants. METHODS Serum BDNF, serum cortisol, and depressive symptoms (per CES-D) were assessed during each trimester and 4-11 weeks postpartum among 139 women (77 Black, 62 White). Low birth weight (<2500g) was determined via medical record. RESULTS Serum BDNF declined considerably from 1st through 3rd trimesters (ps≤0.008) and subsequently increased at postpartum (p<0.001). Black women exhibited significantly higher serum BDNF during the 1st trimester, 2nd trimester, and postpartum (ps≤0.032) as well as lower serum cortisol during the 2nd and 3rd trimester (ps≤0.01). Higher serum cortisol was concurrently associated with lower serum BDNF in the 2nd trimester only (p<0.05). Controlling for race, serum BDNF at both the 2nd and 3rd trimester was negatively associated with 3rd trimester depressive symptoms (ps≤0.02). In addition, women delivering low versus healthy weight infants showed significantly lower serum BDNF in the 3rd trimester (p=0.004). Women delivering low versus healthy weight infants did not differ in depressive symptoms at any time point during pregnancy (ps≥0.34). CONCLUSIONS Serum BDNF declines considerably across pregnancy in Black and White women, with overall higher levels in Blacks. Lower serum BDNF in late pregnancy corresponds with higher depressive symptoms and risk for low birth weight in Black and White women. However, the predictive value of serum BDNF in pregnancy is specific to within-race comparisons. Potential links between racial differences in serum BDNF and differential pregnancy-related cortisol adaptation require further investigation.