It is important to note, however, that women with a lifetime history of major depression show an amplification of the characteristic post-birth increases in serum IL-6 in the early postnatal period, compared with those with no lifetime history (Maes et al., 2001), perhaps suggesting that lifetime history of depression causes an immune reactivity profile which may predispose to depression in the postnatal period. This evidence concerns the gene IL6 and depressive symptom measurement.