The balance between stress and personal capital during pregnancy and the relationship with adverse obstetric outcomes: findings from the 2007 Los Angeles Mommy and Baby (LAMB) study

Abstract

Stress during pregnancy is a salient risk factor for adverse obstetric outcomes. Personal capital during pregnancy, defined as internal and social resources that help women cope with or decrease their exposure to stress, may reduce the risk of poor obstetric outcomes. Using data from the 2007 Los Angeles Mommy and Baby study (N = 3,353), we examined the relationships between the balance of stress and personal capital during pregnancy, or the stress-to-capital ratio (SCR), and adverse obstetric outcomes (i.e., pregnancy complications, preterm birth (PTB), low birth weight (LBW), and small for gestational age (SGA)). Women with a higher SCR (i.e., greater stress relative to personal capital during pregnancy) were significantly more likely to experience at least one pregnancy complication, PTB, and lower gestational age, but not LBW or SGA. Accounting for pregnancy complications completely mediated the association between the SCR and PTB. Our findings indicate that experiencing greater stress relative to personal capital during pregnancy is associated with an increased risk for pregnancy complications, PTB, and lower gestational age and that pregnancy complications may be a mechanism by which the SCR is related to adverse obstetric outcomes.

Figure 1. A Conceptual Framework for the Relationship between the Balance of Personal Capital and Stress during Pregnancy and Adverse Obstetric Outcomes

The figure illustrates the balance between personal capital and stress during pregnancy. The personal capital score was created using a weighting scheme based on Bronfenbrenner’s ecological model and comprised internal resources, partner support, social network support, and neighborhood support. Proximal resources were weighed more heavily than distal resources as they were posited to have a larger and more direct impact on the individual. As such, internal resources, partner support, social network support, and neighborhood support comprised 32.5%, 27.5%, 22.5%, and 17.5%, respectively, of the overall score. Further, for the composite stress measure, perceived stress was weighted twice as heavily (67%) as severe life events (33%) because while life events may not render the same impact on all individuals, the subjective appraisal of stress arguably has a more direct effect on mental health during pregnancy as well as the behavioral and biological pathways leading to adverse obstetric outcomes. Additionally, severe life events are rare shocks, whereas perceived stress is more likely to be persistent and chronic. Therefore, the figure graphically depicts how each component was weighted and then summed to create the composite measures of personal capital and stress. Finally, the balance between personal capital and stress (empirically captured by the Stress-to-Capital Ratio) is hypothesized to lead to adverse obstetric outcomes.

Figure 2. Distribution of the Stress-to-Capital Ratio (SCR) for 2007 LAMB Study Respondents

Legend: The histogram illustrates the distribution of the Stress-to-Capital Ratio (SCR) scores for the 2007 LAMB study respondents. The blue curve represents a normal distribution fit to the mean and standard deviation of the SCR. The mean SCR for the sample was −0.09, with a standard deviation of 0.45.