This study is the first to our knowledge to test the
impact of predominantly breastfeeding on postpartum
depression, stress, and inflammation using a longitudinal
study design across 6 months postpartum. Overall, we did
not find a benefit of predominantly breastfeeding on
depressive symptom or perceived stress compared to
predominantly bottle feeding, however, our data do
identify PNI effects of breastfeeding versus bottle feeding,
including decreased level of the pro-inflammatory marker
IL-6 and increased levels of salivary cortisol at 8 AM and
8:30 AM in women predominantly breastfeeding that
potentially could have implications for health.