The Relationship Between Prenatal Stress, Depression, Cortisol and Preterm Birth: a Review
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Open Journal of Depression 2013. Vol.2, No.3, 24-31 Published Online August 2013 in SciRes (http://www.scirp.org/journal/ojd) http://dx.doi.org/10.4236/ojd.2013.23006 The Relationship between Prenatal Stress, Depression, Cortisol and Preterm Birth: A Review Kiran Shaikh1*, Shahirose Premji2, Khurshid Khowaja3, Suzanne Tough4, Ambreen Kazi5, Shaneela Khowaja6 1Aga Khan University School of Nursing and Midwifery, Karachi, Pakistan 2University of Calgary, Alberta, Canada 3Director of Nursing Al Noor Hospital, Al Ain and Associate Professor, Aga Khan University, Karachi, Pakistan 4Department of Pediatrics and Community Health, University of Calgary, Alberta, Canada 5Department of Community Health Sciences, Aga Khan University, Karachi, Pakistan 6Aga Khan University School of Nursing and Midwifery, Karachi, Pakistan Email: *[email protected] Received May 20th, 2013; revised June 22nd, 2013; accepted July 3rd, 2013 Copyright © 2013 Kiran Shaikh et al. This is an open access article distributed under the Creative Commons At- tribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preterm birth is one of the most common adverse pregnancy outcomes. Maternal risk factors such as stress and depression have been associated with preterm birth. Preterm infants are at a higher risk of poor growth and neuro developmental outcomes. The objective of this paper is to examine the relationship be- tween maternal stress, depression, cortisol level, and preterm birth. Preterm birth is one of the most com- mon adverse pregnancy outcomes with a global prevalence of 9.6% and one of the major contributors to infant mortality and morbidity. The association between psychosocial stress and preterm birth, although examined for more than 25 years, has not yet been fully established. A systemic review was conducted in which research studies and review articles from 1970 to 2012, published in English, focusing on human subjects, and addressing the relationship between stress, depression, cortisol and preterm birth were in- cluded in this review. The studies examining the relationship between stress, cortisol levels and preterm birth have shown inconsistent findings that may be explained by varied study designs, differences in defin- ing and measuring stress, timing of stress measurement, sample characteristics, and study designs. The relationship between stress, cortisol levels and preterm birth may be multifactorial and complex with premature birth being the final common pathway. A longitudinal cohort study, with a large sample size and multiple measures of stress, depression, and cortisol level, as well as a measure of anxiety and other stress hormone biomarkers may add new knowledge and enhance our understanding about the contribu- tion of psychosocial stress to preterm birth. Keywords: Maternal Stress; Antenatal Stress; Maternal Depression; Preterm Delivery; Preterm Birth; Gestational Age; Low Birth Weights; Cortisol Introduction births. Prematurity and its complications account for almost 30 percent of neonatal deaths (Mathews & Mac Dorman). The cost Preterm birth, defined as “birth before 37 completed weeks” of the hospitalization of preterm birth infant is $5.8 billion rep- (Steer, 2005: p. 1), is one of the most common adverse preg- resenting half of infant hospitalization cost (Russell et al., nancy outcomes. Preterm birth is a global issue, irrespective of 2007). Moreover, stress of hospitalization and fear of losing an region or the level of resources (Beck et al., 2010). All resource infant is traumatic and a source of grief for the family. Besides regions: high, middle, and low report varying degrees of pre- this, the psychological distress and risk of postpartum depres- term birth rates (Beck et al.). The rate of preterm delivery sion increases with having a preterm baby (Hill & Aldag, 2007). ranges from 5% in developed countries to 25% in developing Preterm infants are also at a greater risk of serious health prob- countries (Goldenberg et al., 2008; Steer, 2005). Africa (11.9%), lems, such as cerebral palsy, blindness, breathing problems, and followed by North America (10.6%) and Asia (9.1%) have the cognitive learning disabilities (Green et al., 2005; Latengresse, highest rates of preterm birth. The estimated global rate of pre- 2009; Rafati et al., 2005). Kramer et al. (2009) stated that un- term birth is 9.6% which is close to the rate of preterm birth derstanding the etiology of preterm birth will facilitate early rate in Asia (Beck et al.). Studies indicate that preterm birth has identification of mothers at risk for preterm birth. Imple- an impact on the rate of infant mortality and morbidity (Ma- mentation of early intervention strategies for these high risk thew & Mac Dorman, 2007). According to the World Bank mothers will decrease preterm birth thereby reducing the (2008), the global infant mortality rate was 46 per 1000 live burden of preterm birth (i.e., infant mortality, morbidity, *Corresponding author. postpartum depression, parental role stress, and financial Copyright © 2013 SciRes. 24 K. SHAIKH ET AL. stress). nals such as Journal of Midwifery and Women Health, Research There are many maternal factors which are associated with and Health, Journal of Obstetrics, Gynecology and Neonatal preterm birth and these have been extensively highlighted in Nursing, American Journal of Obstetrics and Gynecology, and literature, such as low socioeconomic status, maternal age, and Lancet and American Journal of Epidemiology as they are the low level of education, anemia, inadequate prenatal care, psy- most relevant sources for new knowledge in maternal and child chosocial stress, obstetric complications, smoking, and mater- health. Also, the reference lists of all relevant articles were re- nal history of preterm delivery (Allen, 2001; Astolfi & Zonta, viewed to identify additional articles. Articles were included if 1999; Hsieh et al., 2005; Ismail, Zaidi, & Maqbool, 2003; Ma- they examined the relationship between stress or depression, valankar, Gray, & Trivedi, 1992). The relationship of many of cortisol level and preterm birth. these factors to preterm birth is clear. However, the association between psychosocial stress and preterm delivery, although Findings examined for more than 25 years, has not yet been fully estab- lished (Dunkel-Schetter, 1998; Latendresee, 2009). Overview of the Included Studies Stress and depression alters the hypothalamic-pituitary-ad- A total of 49 articles were found examining the relationship renal (HPA) axis whereby corticotrophin-releasing-hormone between stress, depression, cortisol and preterm birth. Of these, (CRH) is secreted by the hypothalamus which in turn stimulates 27 articles were excluded as they focused on infant cortisol level, the pituitary gland to secrete adrenocorticotrophic hormone non-pregnant women, fetal cortisol, and birth weight of the (ACTH). ACTH stimulates the adrenal cortex to secrete cortisol infant rather than examine the relationship between the variables hormone (Diego et al., 2009; Giurgescu, 2009; Ruiz et al., 2001) of interest. Therefore, a total of 22 articles were selected for the and the adrenal medulla to secrete norepinephrine and epineph- review as given their focuses on the relationship between stress, rine (Holzman et al., 2009). Increased cortisol levels further depression, cortisol and preterm birth (see Figure 1). Although signal the hypothalamus and pituitary gland in a negative feed- everal studies have attempted to understand the psychosocial back loop to decrease CRH production. However, in depressed risk factors associated with preterm birth, the relationships exa- patients the negative feedback loop malfunctions resulting in mined have varied between studies. For instance, a number of excess production of CRH; hence cortisol. Simultaneously, stress researches examined the relationship between stress, depression alters the immune function and increases the production of cy- and preterm birth without considering cortisol (Copper et al., tokines. A negative feedback loop exists between the HPA axis 1996; Dole et al., 2003; Jesse, Swanson, Newton, & Morrow, and the immune system. Cytokines stimulate the HPA axis and 2009; Jesse, Seaver, & Wallace, 2003; Wadhwa, Culhane, Vit- lead to excessive secretion of cortisol (Behrman & Butler, gina, Brave et al., 2001; Khashan et al., 2009; Whitehead et al., 2007). In acute stress, glucocorticoids suppress the inflamma- 2002; Zhu et al., 2010). Two studies examined the relationship tory process but in chronic stress glucocorticoids can enhance between stress and cortisol only (Harville et al., 2009; Obel et inflammation (Behrman & Butler). The increased secretion of al., 2004) while five studies only explored the relationship be- CRH, ACTH, cortisol, and cytokines stimulate prostaglandin tween cortisol and preterm birth (Campbell, Challis, DaSilva, & secretion which is responsible for the contraction and dilation Bocking, 2005; Phocas, Sarandakou, & Rizos, 1990; Mazor et of the smooth muscle, could lead to preterm labor and prema- al., 1994, 1996; Sandman et al., 2006). Of the 22 articles seven ture rupture of membrane. Therefore, changes in the hormonal determined the relationship between stress or depression, milieu due to stress and depression may contribute to premature initiation of labor and preterm birth. Given the high prevalence of psychological disorder in wo- men during pregnancy (Bennett, Einarson, Taddio, Koren,