Maternal prenatal anxiety and corticotropin-releasing hormone associated with timing of delivery.
Mancuso RA, Dunkel Schetter C, Rini CM et al.;
Commented by , 22 Nov 2004
Introduction
The high rate of preterm deliveries in the United States is a troubling public health issue, a leading cause of perinatal morbidity and mortality. While prenatal anxiety and increased levels of maternal plasma corticotropin-releasing hormone (CRH) have each been associated with preterm birth, prior research has not evaluated these variables together.
Purpose
To prospectively examine how pregnancy-specific anxiety and CRH levels are related to gestation length.
Methods
282 ethnically and socio-economically diverse women were recruited from prenatal clinics in Los Angeles. Prepartum psychosocial assessments, health history and physiologic measures occurred at 18-20 weeks (Time 1), and 28-30 weeks gestation (Time 2).
The Prenatal-Specific Anxiety Scale (PSAS), a 4-item 5-point likert measure, was developed by the authors as a context-specific measure of anxiety. The PSAS and CRH levels were measured at Times 1 and 2.
Univariate analyses of variance tested the relationship of both ethnicity and type of labour with prenatal anxiety, CRH and gestational age at delivery. Pearson product-moment correlations were calculated to test the hypothesis that at both Times 1 and 2, CRH and prenatal anxiety would be negatively associated with gestational age at birth.
Where significant, hierarchical regression analyses then tested whether CRH mediated to relationship between prenatal anxiety and gestational age at delivery.
Results
There was no relationship between prenatal anxiety or CRH levels on type of labour. No ethnic differences were found for CRH levels or gestational age at delivery. African-American women, however, reported greater prenatal anxiety than European-American at Times 1 and 2.
For Time 1, only a significant negative correlation between CRH and gestational age at delivery was found (r = -0.37, p < .01). For Time 2, both pregnancy-specific anxiety and CRH were negatively correlated with gestational age at birth (r = -0.19, r = -0.41, respectively, p < .01). In addition, pregnancy-specific anxiety and CRH were positively correlated (r = 0.15, p < .05).
Using hierarchical regression analyses, CRH at Time 2 mediated the relationship between pregnancy-specific anxiety and gestational age at delivery, controlling for confounding factors (medical risk, income, education and parity) (p < .01). Finally, women who delivered preterm (< 37 weeks) had significantly higher rates of CRH at Times 1 and 2 (p < .001).
Dr Ghatavi's comments
Several limitations bear discussion. As the authors note, analyses of mediation carry inherent limitations and are controversial in psychosocial research. Thus, the mediating impact of CRH between prenatal anxiety and earlier delivery should be viewed as a preliminary causal pathway. The authors did, however, account for important confounding variables, increasing the reliability of their findings.
The selected measure of stress and anxiety developed by the authors, the PSAS, carried only adequate internal reliability. A more systematically developed measure, with higher internal reliability, may have strengthened the modest relationship between prenatal anxiety and gestational age at delivery in this study.
Notwithstanding these limitations, the authors have made an important contribution to the literature. This is the first study to prospectively link both psychosocial and neuroendocrine factors to preterm delivery. These preliminary findings add fodder to the justification of developing psychosocial interventions with the potential to modify prenatal anxiety and in turn target a major public health concern.
The ethnic differences in prenatal anxiety deserve future study, and may inform targeted interventions.