We read with interest the article by Forman et al.1, and would like to congratulate them on their enormous effort in conducting this study of such a large cohort. However, our interpretation of the results of the study is somewhat at variance with the opinions of the investigators.

First, it should be pointed out that the low prevalence of postpartum depression found in this study was low point prevalence and not period prevalence. Using the same instrument (i.e. the Edinburgh Postnatal Depression Scale), Cox et al.2 have shown that while the point prevalence of depression at 6 months postpartum was 9.1%, the six-month period prevalence was 13.8%. Thus a low point prevalence rate does not equate to low prevalence of postpartum depression in a certain population.

Second, the literature suggested that the rates of depression are similar between pregnancy and the postpartum period3, and no difference in either the six-month prevalence or period prevalence could be demonstrated between postnatal and non-pregnant control women2. In addition, the onset of depression was threefold higher in the first five weeks postpartum2 and lasting up to three months4, and the risk factors identified indicated that the depressed women were those with either pre-existing depression or with a disposition towards depression that was unmasked by pregnancy. Taken together with the aforementioned reports, we suspect that what was found in this study was not the prevalence of postpartum depression, but rather the prevalence of depression in women who happened to have a predilection to depression, and which might have been unmasked by childbirth, four months before the administration of the Edinburgh Postnatal Depression Scale. We also suspect that the point prevalence found in this study would be no different from that in non-pregnant women in the same region. Could the investigators explain the reason for performing the screening at four months postpartum, and inform us of the incidence of the various forms of depression in the non-pregnant or overall population in their country?


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  2. References
  • 1
    Nielsen Form D., Videbech P., Hedegaard M., Dalby Salvig J., Secher N.J.. Postpartum depression: identification of women at risk. Br J Obstet Gynaecol 2000;107: 12101217.
  • 2
    Cox J.L., Murray D., Chapman G.. A controlled study of the onset, duration and prevalence of postnatal depression. Br J Psychiatry 1993;163: 2731.
  • 3
    O'Hara M.W., Zekoski E.M., Phillips L.H., Wright E.J.. Controlled prospective study of postpartum mood disorders: comparison of childbearing and nonchildbearing women. J Abnorm Psychol 1990;99: 315.
  • 4
    Cox J.L., Rooney A., Thomas P.F.. How accurately do mothers recall postnatal depression? Further data from a 3-year follow-up study. J Psychosom Obstet Gynecol 1984;3: 185187.