The physiological changes in peripartum may affect symptoms of depression and impact diagnostic judgments in the peripartum. The sharp fall in cortisol and CRH after childbirth suggests that the HPA axis characteristics of postpartum depression are different from melancholic depression, the latter being characterized by high cortisol levels.

A modified version of the SCID was used to assess symptoms of depression and melancholic and atypical subtypes in pregnancy and the postpartum period. Secondly, we investigated the diurnal output of saliva cortisol in women with and without symptoms of depression at 7.5 weeks postpartum, and non perinatal controls.

The antenatal symptom pattern (n = 892 women) was different from the postnatal. The sensitivity of the symptoms ranged from 0.7% to 51.6%, and specificity from 61.3% to 99.1%. The best discriminating symptoms were motor retardation/agitation and concentration antenatally, and motor retardation/agitation, concentration and fatigue postnatally. In a subgroup of this sample (n = 449) 17% of the cohort met SCID criteria for a depression at least once in pregnancy: melancholic depression (2.4%), atypical depression (4.4%), and non specified depression (10.2%). Mood reactivity, distinct quality of mood and sleep pattern discriminated between the two groups. There was no increase in cortisol over the day, however a significant difference in diurnal pattern of cortisol between postnatally depressed and non-depressed women.

These findings suggest that perinatal depression has different associated symptoms from depression at other times. The cortisol pattern in the postnatally depressed women is similar to that reported for PTSD and atypical depression.