Research That Matters (January 17 - 20, 2008)

Purpose: Preterm birth is one of the most persistent and least understood public health concerns in the United States (Green et al., 2005). In 2002, 17.7% of Black singletons compared to 11% of White singletons were born before 37 weeks of gestation (Martin et al., 2003). Disorders related to preterm birth, such as low birth weight, are leading causes of Black infant mortality and pose a serious public health concern (Mathews et al., 2002). Despite the long tradition of research on the role of maternal stress and adverse birth outcomes, whether maternal depressive symptoms have any adverse effect on preterm birth remains unknown (Hoffman & Hatch, 2000). Despite the conflicting results, what is clear from the work is depressive symptoms may be a marker of a still undetected risk factor for preterm birth among certain subpopulations of women. In the present study, we prospectively examined the association between prepregnancy depressive symptoms and preterm birth in a cohort study of Black and White women. First, we hypothesize that an elevated level of prepregnancy depressive symptoms has an independent effect on preterm birth. Secondly, we hypothesize that the high prevalence of prepregnancy depressive symptoms among Black women mediates the association between race and preterm birth. Methods: We use longitudinal data from the Coronary Artery Risk Development in Young Adults (CARDIA) Study. Analyses were designed to examine whether depression may mediate the association between race and preterm delivery (Baron & Kenny, 1986). Logistic regression analyses with preterm birth as the outcome and race as the main predictor were conducted, followed by a model with depressive mood as the outcome variable and race as the main predictor. A final model with preterm birth as the outcome and both race and depressive mood as predictors was conducted. Analyses stratified by race were conducted to examine the influence of prepregnancy depressive mood on preterm delivery by race. Results: Controlling for known covariates, Black women were more likely to experience preterm births compared to White women (OR = 2.3; 95% CI: 1.2, 4.6), while those who reported a high level of prepregnancy depressive symptoms were also more likely to deliver preterm infants (OR = 1.04; 95% CI: 1.01, 1.1). Additional logistic regression analyses revealed that among Black women, reporting an elevated level of prepregnancy depressive symptoms was positively associated with the delivery of preterm infants (OR = 1.1, 95% CI: 1.02, 1.1). Conclusions: To our knowledge, this is the first study that prospectively examined the association of depressive symptoms prior to the antenatal period and the incidence of preterm birth. Our study highlights the importance of examining depression status during the prepregnancy period with respect to the occurrence of preterm birth, and may enhance our understanding of the role of depression in the etiology of the Black-White difference in preterm birth.