Caregiving to very low birthweight infants: a model of stress and immune response.

Mothers of preterm, very low birthweight (< or = 1500 g; VLBW) infants experience the stress of caring for small, fragile infants at the same time that they are recovering from the relative immunosuppression of pregnancy and when many health behaviour changes (e.g., nutrition) occur which also may influence immune status. The purpose of this study was to examine changes in anxiety and depression and in health behaviors, as well as lymphocyte proliferation and natural killer cell activity in mothers of preterm, VLBW infants compared to mothers of healthy term infants. Mothers of preterm VLBW infants have decreased in vitro lymphocyte response to mitogens compared to mothers of healthy term infants over time, and this difference could not be explained by anxiety, depression, or health behaviors. However, among mothers of VLBW infants, anxiety was related to decreased lymphocyte proliferation response at 1 month postpartum. There was no relationship between maternal depression and lymphocyte proliferative response in mothers of term infants. Natural killer cell activity did not differ between the two groups of mothers, nor was there a relationship between natural killer cell activity and maternal anxiety, depression, or health behaviors. Thus, lymphocyte proliferative response to mitogens may be an important biologic market of increased stress in mothers of VLBW infants in the first couple of months postpartum.