Maternal Perceived Stress during Pregnancy Increases Risk for Low Neonatal Iron at Delivery and Depletion of Storage Iron at One Year

Abstract

Objective: To investigate the impact of maternal stress during pregnancy on newborn iron and stage 1 iron deficiency at 1 year of age.

Study design: In total, 245 mothers and their newborn infants (52% male; 72% white) were recruited at the Meriter Hospital Birthing Center on the basis of known risk factors for iron deficiency. Umbilical cord blood hemoglobin and zinc protoporphyrin/heme (ZnPP/H) were determined to evaluate erythrocyte iron and plasma ferritin was determined to reflect storage iron. Mothers retrospectively reported stress experienced previously during pregnancy on a 25-item questionnaire. Blood was also was collected from 79 infants who were breastfed at 1 year of age.

Results: Maternal recall of distress and health concerns during pregnancy correlated with cord blood ZnPP/H indices (r = 0.21, P < .01), even in the absence of major traumatic events. When concurrent with other known risks for iron deficiency, including maternal adiposity, socioeconomic status, and race, maternal stress had a summative effect, lowering cord blood iron. At 1 year, 24% of infants who were breastfed had moderate iron deficiency (plasma ferritin <12 µg/L). Higher cord blood ZnPP/H was predictive of this moderate iron deficiency (95% CI 0.26-1.47, P = .007). When coincident with maternal reports of gestational stress, the likelihood of low plasma ferritin at 1 year increased 36-fold in breastfed infants as compared with low-stress pregnancies (95% CI 1.33-6.83, P = .007).

Conclusions: Maternal recall of stress during pregnancy was associated with lower iron stores at birth. High cord blood ZnPP/H, reflecting low erythrocyte iron, was correlated with the likelihood of stage 1 iron deficiency at 1 year, when rapid growth can deplete storage iron in breastfed infants.

Keywords: iron deficiency; psychosocial; risk factors; sex.

Figure 1

(A) Correlation of delta ZnPP/H in cord blood with maternal perceived stress scores (r = 0.22, p< .001). (B) Correlation of delta ZnPP/H with maternal stress was significantly higher in infants born to mothers who had a BMI greater than or equal to 35 at the time of delivery (p< .01). (C) Correlation of maternal stress and CB RE-ZnPP/H in female infants born to mothers of low socioeconomic status (p =.01).

Figure 2

A) The predicted probability (and 95% confidence intervals) of low Ferr indicative of depleted iron stores (<12 μg/L) at 1 year of age, estimated with logistic regression from CB ZnPP/H values at birth. Jittered circles denote each individual infant. The odds of having lower Ferr increased significantly by 1.03 for every unit increase in ZnPP/H at birth. (B) Probability of stage I iron deficiency at 1 year by iron stores at birth (assessed using Re-ZnPP/H) and pregnancy stress reported by mothers. * indicates significant difference between groups.