Effects of Stress on Pregnancy

Publication Date: 2021

Abstract

Natural disasters can have broad sweeping effects on the physical and psychological health of populations. Pregnant individuals may be at particular risk from these disasters. Following Hurricane Florence’s landfall in Wilmington, North Carolina in 2018, we assessed maternal distress in pregnant women through in person (n=38) and online (n=64) interviews. We assessed hardship due the hurricane (Hurricane Experience Scale), distress (Impact of Event Scale–Revised), perceived social support (Multidimensional Scale of Perceived Social Support), and food security (Household Food Security Survey). Married women in this study were more likely to be older, more educated, have greater food security, and identify as white non-Hispanic. Although we found no difference in disaster-based hardships associated with marital status, unmarried women experienced higher rates of distress associated with the hurricane. Surprisingly, this distress was not directly associated with food security or perceived social support. These differences may reflect more subtle differences in resource access and support across marital status and require further investigation.

Overview

Exposure to disasters can represent a major source of stress (Galea et al., 2005¹; Norris et al., 2002a²; Norris et al., 2002b³), which can affect both physiological and psychological health outcomes (Stinson et al., 2000⁴). Stressful conditions might make it difficult for people to self-manage health and illness, which might be further exacerbated by difficulty accessing health care following disasters (Rabkin et al., 2018⁵).

Pregnant women face specific burdens, such as disrupted access to obstetric care (American College of Obstetricians and Gynecologists [ACOG], 2010⁶), which could exacerbate their stress during or following a natural disaster. Stress during pregnancy affects not only maternal well-being, but can affect short- and long-term health outcomes among offspring (Beydoun & Saftlas, 2008⁷; Entringer at al., 2010⁸; Glover et al., 2010⁹; Hocher, 2007¹⁰; King et al., 2012¹¹; Kingston, 2011¹²), such as risk of low birthweight and preterm birth (Beydoun & Saftlas, 2008; Hobel et al., 2008¹³); cognitive, behavioral, and psychomotor development (Kingston & Tough, 2014¹⁴; Kingston et al., 2012¹⁵), immune function (Veru et al., 2014¹⁶); and metabolic outcomes in childhood, adolescence, and adulthood (Entringer et al., 2010). This is thought to reflect effects of maternal stress hormones, which can cross the placental barrier and affect fetal development (Lazinski et al., 2008¹⁷), as well as epigenetic changes in the placenta and fetus (Monk et al., 2012¹⁸).

The mental health risks of natural disaster exposure vary based on sociodemographic characteristics. For example, most studies show that younger adults are at greater risk of distress following disasters than older adults (Norris et al., 2002b). Furthermore, symptoms of distress are usually elevated among ethnic minorities and people with lower education or income (Norris et al., 2002b). Risk might also vary based on marital and parental status. For example, past studies show higher distress among parents (whether married or single) compared to people without children (Solomon et al., 1993¹⁹). Furthermore, some studies suggest that marriage is a risk factor for distress following technological disasters, such as building collapses or industrial accidents (Norris et al., 2002b), although there are fewer published data following natural disasters. Unmarried pregnant women may be at particular risk due to reduced access to resources that might exacerbate hardship and a lack of social support (ACOG, 2010; Howells et al., 2016²⁰; Raatikainen et al., 2005²¹).

In September 2018, Hurricane Florence made landfall in southeastern North Carolina. The storm left thousands of people without power for weeks, displaced from their homes, and with significant loss of income. We developed a study on stress during pregnancy and infant development among women who were pregnant during the hurricane or who became pregnant shortly after.

This study enabled us to:

1. Compare patterns of hardship and distress among married and unmarried pregnant women

2. Examine predictors of distress

3. Examine pathways that might mediate potential differences, including hurricane exposure, social support, and food security

Methods

Sample Characteristics and Recruitment

Women from the affected areas who were over 18 years old, who were either pregnant during the hurricane or became pregnant within three months of the hurricane (September - December 2018) were invited to participate. We recruited women for in person (n=38) and online (n=64) questionnaires. We posted study details on local social media pages focusing on women’s health and pregnancy, as well as a page created specifically for the study. We also distributed posters in Spanish and English around the affected area. Finally, we worked with a local medical clinic (MedNorth) that focuses on serving women of low socioeconomic status. Health care professionals from this clinic shared information about the study with potentially eligible women.

Questionnaire

The questionnaire included questions on sociodemographic characteristics and details of their pregnancy. We assessed hardship due to the hurricane with the Hurricane Experience Scale, a multi-item scale assessing categories of threat, loss, scope, and change due to the event. This was adapted from studies of prenatal stress due to natural disasters by the Stress in Pregnancy International Alliance (King et al., 2015²²). We used the Impact of Event Scale – Revised (Weiss & Marmar, 1997²³) to assess distress in response to the hurricane. We used the Multidimensional Scale of Perceived Social Support (Zimet et al., 1990²⁴) to measure perceived support from family, friends, and a significant other. Finally, we used the U.S. Household Food Security Survey Module (USDA, 2012²⁵) to assess food security. Further details on this study can be found in Howells et al., 2020 (Howells et al., 2020²⁶).

Preliminary Analyses

We analyzed descriptive characteristics and differences based on marital status using one-way ANOVA and chi-squared analyses. We used linear regression to analyze predictors of distress. Analyses were conducted with SPSS version 25 (IBM Statistics). To further probe relationships underlying differences in distress by marital status, we used two moderated mediation models to test whether relationships between hurricane experience and distress were mediated by either social support or food security, and whether these patterns were moderated by marital status. Models were tested using the PROCESS macro for SPSS using bootstrapping procedures (Hayes, 2018²⁷).

Results of Preliminary Analyses

Descriptive Statistics

Age varied significantly by marital status (p<0.001); age was significantly higher among married women than the other two groups. Education differed among groups (p<0.001), with more married women completing University (74.2%) compared to single women (11.1%) or those living with a partner (37.5%). Race/Ethnicity also differed among groups (p=0.001); although most participants in all groups were white non-Hispanic, a greater proportion of single participants and those living with partners were non-White compared to married women. This sociodemographic sample is generally representative of the general population in the area (Howells et al., 2020). We do not have data to assess the generalizability of the hardship and distress patterns in the current sample to that of the general population.

Hardship due to the hurricane was similar among married and unmarried women (p=0.207), but distress differed significantly among these groups (p=0.001). Distress was highest among single women and lowest among married women. Finally, food security status differed among groups, with married women reporting significantly fewer affirmative responses (indicating greater food security) (p<0.001) and higher prevalence of food security (p=0.003) than the other two groups (Howells et al., 2020).

Predictors of distress

Linear regression analyses showed no relationships among distress and maternal age, number of children, or education. Marital status was a significant predictor of distress (p=0.014), explaining 9.8% of unique variance. Hurricane experience was also a significant predictor of distress (p=0.003), explaining 4.3% of unique variance. The series of models testing interaction effects showed no significant interactions between marital status and hurricane experience (p=0.236), food security (p=0.128), or social support (p=0.561) (Howells et al., 2020).

Mediation analyses

Consistent with linear regression results, analyses of moderated mediation testing whether relationships between hurricane experience and distress were mediated by food insecurity or by social support showed no significant indirect effects, and no moderation by marital status (food security index of moderated mediation = 0.00, 95% CI = -0.16, 0.11; social support index of moderated mediation = 0.01, 95% CI = -0.10, 0.12).

Discussion

We assessed the impact of Hurricane Florence among pregnant women and identified unmarried pregnant women as being at a particularly high risk for distress associated with the event. The detailed results of this study can be found in Howells et al., 2020.

Although we found no differences in disaster-based hardships associated with marital status, unmarried women experienced greater distress during the hurricane and hurricane recovery than their married peers. This does not seem to be due to differences in factors such as number of children or degree of hardship, which were similar among groups, nor factors such as education or food security that differed between married and unmarried women but were not significant contributors to distress in this study. Rather, the increased risk of distress among unmarried women likely reflects complex intersections between these and other risk or protective factors such as access to resources that warrant further analyses.

Marital status can impact a woman’s access to care under non-emergency situations. For instance, unmarried women utilize less prenatal care (Glei et al., 2003²⁸; McCaw-Binns et al., 1995²⁹; Raatikainen et al., 2005), have poorer health (Wood et al., 2007³⁰), and experience worse pregnancy outcomes (Raatikainen et al., 2007³¹) and more surgical interventions during delivery (Howells et al., 2016). In the United States these differences have been associated with married women’s increased access to the social and financial resources necessary to access care (Kalinka et al., 2003³²).

Past studies show that the experience of other stressful life events and adverse mental health before a disaster can increase risk of distress. These likely account for part of the higher risk of distress among unmarried pregnant women. Data from the United States show that unmarried pregnant women were more than twice as likely to experience multiple prenatal stressful life events as married pregnant women (Mukherjee et al., 2017³³). Furthermore, unmarried pregnant women have greater risk for common mental disorders than their married counterparts (Biaggi et al., 2016³⁴). Data from Project Viva in the United States show that risk of antenatal depressive symptoms was around twice as high among women who were not married or cohabiting compared to married women. Adjustment for social support dampened but did not eliminate these differences (Rich-Edwards et al., 2006³⁵). Incorporating these variables into future studies following natural disasters might help to highlight risk factors for distress among unmarried women.

Further studies are needed to identify the variables underlying these differences. Investigation into the co-occurrence of social inequalities and natural disasters would enable us to identify the syndemic consequences of these experiences on maternal and infant health (Singer, 2009³⁶). Our results highlight the vulnerability of this population to distress during and following natural disasters and the need for larger and more detailed studies to outline the sources of this vulnerability.

This study yielded a socioeconomically diverse sample that has allowed us to begin to investigate risk factors for distress among pregnant women following the hurricane. In particular, few previous studies have specifically assessed marital status in their modeling of maternal stress due to natural disasters. Follow-up of this sample is planned over time to evaluate relationships between prenatal stress and various measures of infant development.

References