In this prospective study, a sample of 86 postpartum women was compared with a sample of 75 women from a random period of 8 consecutive days out of puerperium. Symptoms were evaluated each day using the Blues Questionnaire. Postpartum women and women out of puerperium showed a different distribution of percentile scores on the scale on the third, fourth and fifth days. The postpartum symptom peak occurred on the fifth day. Symptoms more significantly associated with the third, fourth and fifth postpartum days were overemotionalism and oversensitivity. It is concluded that maternity blues in Brazilian women appear to be characterized by maternal mental state alterations occurring on the third, fourth and fifth days postpartum. MB seems to be better defined as an emotional oversensitivity syndrome of cross-cultural dimension than as depression.