Occupational studies have shown an association between elevated Mn exposure and depressive
symptoms. Blood Mn (BMn) naturally rises during pregnancy due to mobilization from
tissues, suggesting it could contribute to pregnancy and postpartum depressive symptoms.
To assess the association between BMn levels during pregnancy and postpartum depression
(PPD), creating opportunities for possible future interventions. We studied 561 women
from the reproductive longitudinal Programming Research in Obesity, Growth, Environment,
and Social Stressors (PROGRESS) cohort in Mexico City. BMn was measured at the 2 nd
and 3 rd trimesters, as well as delivery. The Edinburgh Postnatal Depression Scale
(EPDS) was used to assess PPD symptoms at 12-months postpartum. We used a generalized
linear model assuming a Poisson distribution to assess the association between BMn
levels and PPD, with adjustments for age, stress and depressive symptoms during pregnancy,
education, socioeconomic status, and contemporaneous blood lead levels. The mean ±
standard deviation (SD) EPDS score at 12-months postpartum was 6.51 ± 5.65, and 17.11%
of women met the criteria for possible PPD (score ≥ 13). In adjusted models, BMn during
the 3 rd trimester (β: 0.13, 95% CI: 0.04–0.21) and BMn levels averaged at the 2
nd and 3rd trimester (β: 0.14, 95% CI: 0.02–0.26) had a positive association with
EPDS scores at 12 months postpartum. BMn at the 2 nd trimester (β: 0.07, 95% CI:
−0.09–0.22) and delivery (β: 0.03, 95% CI: −0.04–0.10) had a non-significant positive
association with EPDS scores at 12-months postpartum. Stress and depressive symptoms
during pregnancy was associated with higher EPDS scores at 12-months postpartum in
all of the adjusted models but were only significant when either BMn during 3 rd
trimester or BMn averaged across 2 nd and 3 rd trimester was assessed as the exposure.
Our results demonstrate that elevated BMn levels during pregnancy predict PPD symptoms
and could be a potential pathway for intervention and prevention of PPD.