Poverty and Prenatal Stress: Effects on Birth Outcomes

Background and Significance

Prenatal stress, which leads to high levels of cortisol and other hormones, is damaging both to the mother and to the developing fetus. Through a series of biological mechanisms, a developing fetus responds to the mother’s stress by adapting physiologically, putting him/her at risk for future multiple stress-related pathologies, including poor physical and cognitive development. Populations most at risk for prenatal stress, those in poverty and those who are discriminated against, are the same vulnerable populations for whom the field of social work commonly advocates.

High levels of prenatal stress also contribute to adverse birth outcomes (low birthweight, preterm birth, and small head circumference) by making women vulnerable to infections, which is associated with premature delivery, and by restricting growth of the fetus.  High levels of stress are also associated with changes in fetal brain structure and function, learning and behavioral problems, and chronic disease.

Methods

This study examined data from the Pregnancy Risk Assessment Monitoring System (PRAMS), a collaboration between the Centers for Disease Control and Prevention and individual state health departments. Tennessee data from 2009 (1,161 births) were compiled from individual birth certificates and mothers were mailed questionnaire responses to examine the contributions of poverty and stressful life events to fetal development, operationalized as weeks of gestation at delivery, weight at birth, small-for-gestational age, and large-for-gestational age. Stressful life events in the year before birth were measured using a standardized questionnaire of stressful events. Poverty was based on whether the birth was financed by Medicaid.

We used latent class analysis to determine whether there were distinct classes of mothers with quantitative and qualitative differences in stressful life events, and we used logistic regression to determine if these classes predicted poor birth outcomes.

Results

Two distinct classes emerged, marked by a quantitative difference in that the proportion of stressed mothers who experienced stressors was higher overall and also higher for each stressful life event. In addition, there were qualitative disparities in that these differences were higher for some types of stressful life events than for others.

Poverty (Medicaid status) proved to be a positive predictor of all four adverse birth outcomes. More stressful life events were statistically significant only for small-for-gestational-age delivery, however, after accounting for poverty.

Results showed that African-American women had better birth outcomes at younger ages, corroborating the concept of “weathering,” which hypothesizes that African-American women suffer from disproportionate levels of lifetime stress due to disadvantage and discrimination, leading to an overactive stress response system that damages the reproductive system. 

Implications

Social workers in perinatal settings are tasked with assisting pregnant women to get the services they need, responding to infants in need, supporting parent-child relationships, and advocating for change in the health care setting and system. Expansions in assistance programs during pregnancy and after birth, including income assistance, Medicaid, WIC, and maternity leave are needed. More research is needed about how poverty and discrimination damage women’s reproductive systems, as well as to develop effective methods of reducing stress and minimizing stress damage.