"Timing impacts how prenatal psychosocial context affects birth outcomes"

Background: In the United States approximately one in eight babies is preterm.   Approximately thirty percent of preterm births are attributable to endocrine immune changes that are related to stress processing. During pregnancy, the maturing placenta is an active endocrine and immune organ; however, its’ evolving contributions to stress processing has not been well studied.  This study evaluated Adaptive Reproduction as a theory for understanding how environmental stressors and psychoneurological states impact birth outcomes. Two hypotheses were tested: 1) does the impact of stress, depression, tobacco use and social support on adverse birth outcomes vary across the gestation? And 2) does the experience of perinatal intimate partner violence (IPV) affect the timing of the impact of these variables on birth outcomes?

Methods: Multilevel structural equation modeling was performed on data from BabyBEEP (R01 NR05313), a smoking cessation intervention RCT for low-income pregnant women (N=695). Thirty-four percent of the sample experienced perinatal intimate partner violence.

Results: Both hypotheses were supported by the analysis.  When controlling for the other variables, stress and social support have paradoxical effects at different stages of pregnancy. In women experiencing perinatal IPV, depression, particularly prior to 24 weeks, is associated with both low birthweight and preterm birth.

Conclusion: Adaptive reproduction provides a plausible explanation for why psychoneuroimmune alterations lead to preterm birth and low birthweight.  This explains how community and individual level preconceptional and prenatal interventions aimed at enhancing functional social support and stress resilience improve outcomes and suggests modifications in timing of the interventions for enhanced effects.