• HPA axis;
  • Infection;
  • Lactation;
  • Postpartum;
  • Th1/Th2 cytokines

Objective:  To analyze relationships between stress, moods, and immunity in breastfeeding compared to formula-feeding mothers.

Design:  A cross-sectional study of 181 healthy mothers, exclusively breastfeeding or formula feeding, studied at 4 to 6 weeks after childbirth.

Setting:  Mothers were recruited in the postpartum unit of the hospital and then visited in their homes once at 4 to 6 weeks after childbirth for data collection.

Main Outcome Measures:  Stress, mood, infection symptoms, and serum levels of interferon-gamma and interleukin-10 were measured.

Results:  Formula-feeding mothers had evidence of decreased interferon-gamma and a decreased serum Th1/Th2 ratio (interferon-gamma/interleukin-10) when perceived stress, dysphoric moods, and negative life events were high, an effect consistent with depression of cellular immunity. However, women who were breastfeeding did not show these relationships.

Conclusions:  The data suggest that breastfeeding confers some psychoneuroimmunological benefit to mothers, perhaps through prolactin or hypothalamic-hypophyseal-adrenocortical axis stress refractoriness. JOGNN, 35, 599-607; 2006. DOI: 10.1111/J.1552-6909.2006.00083.x