Cytokines, infections, stress, and dysphoric moods in breastfeeders and formula feeders.

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.