Reply to letter to the editor to “Soy isoflavone intake and prevalence of depressive symptoms during pregnancy in Japan: baseline data from the Kyushu Okinawa Maternal and Child Health Study”

Excerpt

We would like to thank Professor Tomoyuki Kawada for his interest in our recent paper [1] published in the European Journal of Nutrition as well as in our other papers [2‐5]. We have conducted two prebirth cohort studies: the Osaka Maternal and Child Health Study and the Kyushu Okinawa Maternal and Child Health Study. Among the citations included in our papers, references [2‐4] regarding the relationship between dietary factors and postpartum depressive symptoms used data from the Osaka Maternal and Child Health Study. With respect to references [1, 5], data from the Kyushu Okinawa Maternal and Child Health Study were used. In the Kyushu Okinawa Maternal and Child Health Study, depressive symptoms during pregnancy were assessed based on the Center for Epidemiologic Studies Depression Scale, while postpartum depressive symptoms were assessed based on the Edinburgh Postnatal Depression Scale. The two outcomes were different; in fact, the prevalence of depressive symptoms during pregnancy was 19.3%, while the prevalence of postpartum depressive symptoms at 3–4 months postpartum was 8.2%. We would prefer not to perform a simultaneous assessment of the two different outcomes. Using baseline data from the Kyushu Okinawa Maternal and Child Health Study, milk intake was not associated with the prevalence of depressive symptoms during pregnancy, while yogurt intake was significantly inversely related to depressive symptoms during pregnancy [6]. Thus, intake of yogurt, but not of milk, was included in the multivariate model in our recent paper [1]. Nevertheless, intake of milk, but not of yogurt, was significantly inversely associated with the risk of postpartum depressive symptoms [5]. These inconsistent results may be ascribed to the two different outcomes. Again, we express our appreciation for Professor Kawada’s comment. …