The occurrence of preterm delivery is linked to pregnancy-specific distress and elevated inflammatory markers across gestation

There is mounting evidence that stress during pregnancy can have detrimental effects on gestation and birth. Existing studies indicate that prenatal stress may increase levels of circulating inflammatory markers that are associated with prematurity and pregnancy complications, suggesting that stress-related changes in the cytokine milieu may increase the risk of poor pregnancy outcome. Previous studies, however, have not clearly connected stress during pregnancy to changes in inflammatory mediators and, in turn, to clinically-relevant outcomes such as premature delivery. The present study sought to directly connect prenatal stress and changes in inflammatory markers to preterm delivery and gestational age at birth (GAB). A sample of 173 women was recruited during the first trimester of pregnancy and followed through delivery. Overall stress, pregnancy-specific distress, and inflammatory markers were assessed early and later in pregnancy, and the predictive value of these measures for preterm birth and GAB was determined. There were significant differences in pregnancy-specific distress, IL-6, and TNF-α between women who delivered prematurely versus those who delivered at term, and elevated levels of pregnancy-specific distress, IL-6, and TNF-α were predictive of shortened GAB overall. Importantly, in many cases, the effects of overall stress and pregnancy-specific distress on GAB were mediated by levels of circulating inflammatory markers. Collectively, these data provide strong evidence that prenatal stress experiences can affect the timing of parturition via alterations in circulating inflammatory mediators, and underscore the need for ongoing research aimed at further understanding the mechanisms and effects of prenatal stress on maternal and infant health.