Ten studies on depression and preterm birth or low birth weight were reviewed. All studies had prospective designs. Of these, four reported nonsignificant effects (Dole et al., 2003; Goldenberg et al., 1996a; Lobel et al., 2000; Misra et al., 2001; Peacock et al., 1995). Three found that prenatal depression in the mother affected fetal growth (Hoffman and Hatch, 2000) and birth weight percentiles (Paarlberg et al., 1999). Two studies reported associations of depression and preterm delivery (Dayan et al., 2002; Jesse et al., 2003; Orr et al., 2002). One found significant effects only among women who were underweight (BMI < 19) before the pregnancy (Dayan et al., 2002). Another was a large study of African American women only (Orr et al., 2002) reporting adjusted OR of 1.96 for spontaneous preterm birth among women in the top 10 percent on a standard depression measure.
Overall, recent prospective studies on depression do not suggest a strong pattern for depression as a general risk for preterm delivery consistent with the results of earlier studies (Copper et al., 1996; Perkin et al., 1993) with some exceptions. For example, depression in African American women seems to be an area worthy of further investigation. Effects of depression on birth weight or fetal growth is also inconsistent but there are some indications that depression may be a risk factor for fetal growth or low birth weight. Further research is needed to clarify this topic of research. Pathways from emotion to low birth weight through health behaviors such as diet and nutrition, substance use, sleep, and inactivity are important to elucidate. Women who are depressed or anxious during pregnancy are unlikely to take care of themselves as adequately as those who are not. Anxiety may be linked to different behavioral implications than depression. Studies of these states also must address their frequent confounding as well. This is a potential topic for follow-up research.
A relatively small number of studies have assessed the effects of daily stressors on preterm birth but have shown nonsignificant results (Paarlberg et al., 1996; Wadhwa et al., 1993). It is possible that these measures do not capture levels of stress exposure high enough to influence pathways to prematurity. Although daily stressors may operate in combination with other stress exposures, such as major life events, and interact with responses such as anxiety or depression to contribute to the risk of preterm birth, they do not seem promising overall for predictive purposes.
Two other bodies of research are relevant to the role of stress and preterm delivery. One is on the effects of occupational or work stress on preterm delivery (Woo, 1997). This area is related to but distinct from