We found that the effect of breastfeeding on maternal
mood differed by both maternal mental health during pregnancy;
and whether mothers intended to breastfeed. To our
knowledge, this study is the first to document this result.
For the majority of mothers who did not show symptoms
of depression before birth, breastfeeding decreased the risk
of PPD among mothers who had intended to breastfeed, but
increased the risk of PPD among mothers who had not
intended to breastfeed.