Preterm birth disparities between states in the United States: an opportunity for public health interventions

Motivations for investigating health inequities in observational epidemiology: a content analysis of 320 studies

OBJECTIVES

To enhance equity in clinical and epidemiological research, it is crucial to understand researcher motivations for conducting equity-relevant studies. Therefore, we evaluated author motivations in a randomly selected sample of equity-relevant observational studies published during the COVID-19 pandemic.

STUDY DESIGN AND SETTING

We searched MEDLINE for studies from 2020 to 2022, resulting in 16,828 references. We randomly selected 320 studies purposefully sampled across income setting (high vs low-middle-income), COVID-19 topic (vs non-COVID-19), and focus on populations experiencing inequities. Of those, 206 explicitly mentioned motivations which we analyzed thematically. We used discourse analysis to investigate the reasons behind emerging motivations.

RESULTS

We identified the following motivations: (1) examining health disparities, (2) tackling social determinants to improve access, and (3) addressing knowledge gaps in health equity. Discourse analysis showed motivations stem from commitments to social justice and recognizing the importance of highlighting it in research. Other discourses included aspiring to improve health-care efficiency, wanting to understand cause-effect relationships, and seeking to contribute to an equitable evidence base.

CONCLUSION

Understanding researchers' motivations for assessing health equity can aid in developing guidance that tailors to their needs. We will consider these motivations in developing and sharing equity guidance to better meet researchers' needs.

Association between F2-isoprostanes and self-reported stressors in pregnant americans of African and European ancestry

Background

Poor birth outcomes such as preterm birth/delivery disproportionately affect African Americans compared to White individuals. Reasons for this disparity are likely multifactorial, and include prenatal psychosocial stressors, and attendant increased lipid peroxidation; however, empirical data linking psychosocial stressors during pregnancy to oxidative status are limited.

Methods

We used established scales to measure five psychosocial stressors. Maternal adverse childhood experiences, financial stress, social support, anxiety, and depression were measured among 50 African American and White pregnant women enrolled in the Stress and Health in Pregnancy cohort. Liquid chromatography-tandem mass spectrometry was used to measure biomarkers of oxidative stress (four urinary F2-isoprostane isomers), to estimate oxidative status. Linear regression models were used to evaluate associations between psychosocial stressors, prenatal oxidative status and preterm birth.

Results

After adjusting for maternal obesity, gestational diabetes, and cigarette smoking, African American women with higher oxidative status were more likely to report higher maternal adverse childhood experience scores (β = 0.16, se = 1.07, p-value = 0.024) and depression scores (β = 0.05, se = 0.02, p = 0.014). Higher oxidative status was also associated with lower gestational age at birth (β = -0.13, se = 0.06, p = 0.04) in this population. These associations were not apparent in Whites. However, none of the cross-product terms for race/ethnicity and social stressors reached statistical significance (p > 0.05).

Conclusion

While the small sample size limits inference, our novel data suggest that psychosocial stressors may contribute significantly to oxidative stress during pregnancy, and preterm birth or delivery African Americans. If replicated in larger studies, these findings would support oxidative stress reduction using established dietary or pharmacological approaches present a potential avenue to mitigate adverse effects of psychosocial stressors on birth outcomes.

Association of maternal education, neighborhood deprivation, and racial segregation with gestational age at birth by maternal race/ethnicity and United States Census region in the ECHO cohorts

Background

In the United States, disparities in gestational age at birth by maternal race, ethnicity, and geography are theorized to be related, in part, to differences in individual- and neighborhood-level socioeconomic status (SES). Yet, few studies have examined their combined effects or whether associations vary by maternal race and ethnicity and United States Census region.

Methods

We assembled data from 34 cohorts in the Environmental influences on Child Health Outcomes (ECHO) program representing 10,304 participants who delivered a liveborn, singleton infant from 2000 through 2019. We investigated the combined associations of maternal education level, neighborhood deprivation index (NDI), and Index of Concentration at the Extremes for racial residential segregation (ICERace) on gestational weeks at birth using linear regression and on gestational age at birth categories (preterm, early term, post-late term relative to full term) using multinomial logistic regression.

Results

After adjustment for NDI and ICERace, gestational weeks at birth was significantly lower among those with a high school diploma or less (-0.31 weeks, 95% CI: -0.44, -0.18), and some college (-0.30 weeks, 95% CI: -0.42, -0.18) relative to a master's degree or higher. Those with a high school diploma or less also had an increased odds of preterm (aOR 1.59, 95% CI: 1.20, 2.10) and early term birth (aOR 1.26, 95% CI: 1.05, 1.51). In adjusted models, NDI quartile and ICERace quartile were not associated with gestational weeks at birth. However, higher NDI quartile (most deprived) associated with an increased odds of early term and late term birth, and lower ICERace quartile (least racially privileged) associated with a decreased odds of late or post-term birth. When stratifying by region, gestational weeks at birth was lower among those with a high school education or less and some college only among those living in the Northeast or Midwest. When stratifying by race and ethnicity, gestational weeks at birth was lower among those with a high school education or less only for the non-Hispanic White category.

Conclusion

In this study, maternal education was consistently associated with shorter duration of pregnancy and increased odds of preterm birth, including in models adjusted for NDI and ICERace.

β3 Receptor Signaling in Pregnant Human Myometrium Suggests a Role for β3 Agonists as Tocolytics

Preterm labor leading to preterm birth is the leading cause of infant morbidity and mortality. At the present time, nothing can reliably halt labor once it begins. The knowledge that agonists of the β2 adrenergic receptor relax airway smooth muscle and are effective in the treatment of asthma led to the notion that β2 mimetics would prevent preterm birth by relaxing uterine smooth muscle. The activation of cAMP-dependent protein kinase by β2 receptors is unable to provide meaningful tocolysis. The failure of β2 agonists such as ritodrine and terbutaline to prevent preterm birth suggests that the regulation of uterine smooth muscle is disparate from that of airway. Other smooth muscle quiescent-mediating molecules, such as nitric oxide, relax vascular smooth muscle in a cGMP-protein kinase G-dependent manner; however, nitric oxide activation of protein kinase G fails to explain the relaxation of the myometrium to nitric oxide. Moreover, nitric oxide-mediated relaxation is blunted in preterm labor, and thus, for this reason and because of the fall in maternal blood pressure, nitric oxide cannot be employed as a tocolytic. The β3 adrenergic receptor-mediated relaxation of the human myometrium is claimed to be cAMP-dependent protein kinase-dependent. This is scientifically displeasing given the failure of β2 agonists as tocolytics and suggests a non-canonical signaling role for β3AR in myometrium. The addition of the β3 agonist mirabegron to pregnant human myometrial strips in the tissue bath relaxes oxytocin-induced contractions. Mirabegron stimulates nitric oxide production in myometrial microvascular endothelial cells, and the relaxation of uterine tissue in vitro is partially blocked by the addition of the endothelial nitric oxide synthase blocker Nω-Nitro-L-arginine. Recent data suggest that both endothelial and smooth muscle cells respond to β3 stimulation and contribute to relaxation through disparate signaling pathways. The repurposing of approved medications such as mirabegron (Mybetriq™) tested in human myometrium as uterine tocolytics can advance the prevention of preterm birth.

County-Level Maternal Vulnerability and Preterm Birth in the US

Importance

Appreciation for the effects of neighborhood conditions and community factors on perinatal health is increasing. However, community-level indices specific to maternal health and associations with preterm birth (PTB) have not been assessed.

Objective

To examine the association of the Maternal Vulnerability Index (MVI), a novel county-level index designed to quantify maternal vulnerability to adverse health outcomes, with PTB.

Design, Setting, and Participants

This retrospective cohort study used US Vital Statistics data from January 1 to December 31, 2018. Participants included 3 659 099 singleton births at 22 plus 0/7 to 44 plus 6/7 weeks of gestation born in the US. Analyses were conducted from December 1, 2021, through March 31, 2023.

Exposure

The MVI, a composite measure of 43 area-level indicators, categorized into 6 themes reflecting physical, social, and health care landscapes. Overall MVI and theme were stratified by quintile (very low to very high) by maternal county of residence.

Main Outcomes and Measures

The primary outcome was PTB (gestational age <37 weeks). Secondary outcomes were PTB categories: extreme (gestational age ≤28 weeks), very (gestational age 29-31 weeks), moderate (gestational age 32-33 weeks), and late (gestational age 34-36 weeks). Multivariable logistic regression quantified associations of MVI, overall and by theme, with PTB, overall and by PTB category.

Results

Among 3 659 099 births, 298 847 (8.2%) were preterm (male, 51.1%; female, 48.9%). Maternal race and ethnicity included 0.8% American Indian or Alaska Native, 6.8% Asian or Pacific Islander, 23.6% Hispanic, 14.5% non-Hispanic Black, 52.1% non-Hispanic White, and 2.2% with more than 1 race. Compared with full-term births, MVI was higher for PTBs across all themes. Very high MVI was associated with increased PTB in unadjusted (odds ratio [OR], 1.50 [95% CI, 1.45-1.56]) and adjusted (OR, 1.07 [95% CI, 1.01-1.13]) analyses. In adjusted analyses of PTB categories, MVI had the largest association with extreme PTB (adjusted OR, 1.18 [95% CI, 1.07-1.29]). Higher MVI in the themes of physical health, mental health and substance abuse, and general health care remained associated with PTB overall in adjusted models. While the physical health and socioeconomic determinant themes were associated with extreme PTB, physical health, mental health and substance abuse, and general health care themes were associated with late PTB.

Conclusions and Relevance

The findings of this cohort study suggest that MVI was associated with PTB even after adjustment for individual-level confounders. The MVI is a useful measure for county-level PTB risk that may have policy implications for counties working to lower preterm rates and improve perinatal outcomes.

Sociodemographic disparities in preterm birth and low birthweight in the State of Georgia: Results from the 2017-2018 Pregnancy Risk Assessment Monitoring System

PURPOSE

To update the overall prevalence of preterm birth (PTB) (<37 weeks gestation) and low birthweight (LBW) (<2,500 g) in the State of Georgia, including rural and urban counties.

METHODS

A sample was drawn from the 2017-2018 Georgia Pregnancy Risk Assessment Monitoring System (PRAMS). In the complete-case data of singleton births (n=1,258), we estimated the weighted percentage prevalence of PTB, LBW, early/late PTB, and moderately/very LBW subcategories in association with maternal sociodemographic characteristics, and the prevalence stratified by rural/urban county of residence. Univariate and multivariate logistic regression models were fitted to estimate the odds ratios (ORs) of PTB and LBW adjusting for selected covariates. Logistic regression results from multiple imputation by chained equations (MICE) were used for comparison.

FINDINGS

The overall rate for PTB was 9.3% and 6.8% for LBW and among them, 2.3% were early PTB, 7.0% were late PTB, 5.4% were moderately LBW (MLBW), and 1.3% were very LBW (VLBW). Non-Hispanic Black women had the highest prevalence of PTB, LBW, early PTB, MLBW, and VLBW, as well as PTB and LBW in urban counties and LBW in rural counties. The odds of PTB (aOR 1.38; 95% CI: 0.81, 2.35) and LBW (aOR 2.68; 95% CI: 1.32, 5.43) were also higher among non-Hispanic Black relative to non-Hispanic White women and among women who received adequate-plus prenatal care compared to inadequate prenatal care.

CONCLUSIONS

Socioeconomic and health disparities created by disadvantage should be a focus of state policy to improve neonatal outcomes in the State of Georgia.

Bioengineering Approaches for Placental Research

Research into the human placenta's complex functioning is complicated by a lack of suitable physiological in vivo models. Two complementary approaches have emerged recently to address these gaps in understanding, computational in silico techniques, including multi-scale modeling of placental blood flow and oxygen transport, and cellular in vitro approaches, including organoids, tissue engineering, and organ-on-a-chip models. Following a brief introduction to the placenta's structure and function and its influence on the substantial clinical problem of preterm birth, these different bioengineering approaches are reviewed. The cellular techniques allow for investigation of early first-trimester implantation and placental development, including critical biological processes such as trophoblast invasion and trophoblast fusion, that are otherwise very difficult to study. Similarly, computational models of the placenta and the pregnant pelvis at later-term gestation allow for investigations relevant to complications that occur when the placenta has fully developed. To fully understand clinical conditions associated with the placenta, including those with roots in early processes but that only manifest clinically at full-term, a holistic approach to the study of this fascinating, temporary but critical organ is required.

Racial and geographic variation in effects of maternal education and neighborhood-level measures of socioeconomic status on gestational age at birth: Findings from the ECHO cohorts

Preterm birth occurs at excessively high and disparate rates in the United States. In 2016, the National Institutes of Health (NIH) launched the Environmental influences on Child Health Outcomes (ECHO) program to investigate the influence of early life exposures on child health. Extant data from the ECHO cohorts provides the opportunity to examine racial and geographic variation in effects of individual- and neighborhood-level markers of socioeconomic status (SES) on gestational age at birth. The objective of this study was to examine the association between individual-level (maternal education) and neighborhood-level markers of SES and gestational age at birth, stratifying by maternal race/ethnicity, and whether any such associations are modified by US geographic region. Twenty-six ECHO cohorts representing 25,526 mother-infant pairs contributed to this disseminated meta-analysis that investigated the effect of maternal prenatal level of education (high school diploma, GED, or less; some college, associate's degree, vocational or technical training [reference category]; bachelor's degree, graduate school, or professional degree) and neighborhood-level markers of SES (census tract [CT] urbanicity, percentage of black population in CT, percentage of population below the federal poverty level in CT) on gestational age at birth (categorized as preterm, early term, full term [the reference category], late, and post term) according to maternal race/ethnicity and US region. Multinomial logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CIs). Cohort-specific results were meta-analyzed using a random effects model. For women overall, a bachelor's degree or above, compared with some college, was associated with a significantly decreased odds of preterm birth (aOR 0.72; 95% CI: 0.61-0.86), whereas a high school education or less was associated with an increased odds of early term birth (aOR 1.10, 95% CI: 1.00-1.21). When stratifying by maternal race/ethnicity, there were no significant associations between maternal education and gestational age at birth among women of racial/ethnic groups other than non-Hispanic white. Among non-Hispanic white women, a bachelor's degree or above was likewise associated with a significantly decreased odds of preterm birth (aOR 0.74 (95% CI: 0.58, 0.94) as well as a decreased odds of early term birth (aOR 0.84 (95% CI: 0.74, 0.95). The association between maternal education and gestational age at birth varied according to US region, with higher levels of maternal education associated with a significantly decreased odds of preterm birth in the Midwest and South but not in the Northeast and West. Non-Hispanic white women residing in rural compared to urban CTs had an increased odds of preterm birth; the ability to detect associations between neighborhood-level measures of SES and gestational age for other race/ethnic groups was limited due to small sample sizes within select strata. Interventions that promote higher educational attainment among women of reproductive age could contribute to a reduction in preterm birth, particularly in the US South and Midwest. Further individual-level analyses engaging a diverse set of cohorts are needed to disentangle the complex interrelationships among maternal education, neighborhood-level factors, exposures across the life course, and gestational age at birth outcomes by maternal race/ethnicity and US geography.

Ecological momentary assessment of stress, racism and other forms of discrimination during pregnancy using smartphone technology

BACKGROUND

In the United States, there are considerable racial inequities in adverse perinatal outcomes. Exposure to racism, sexism, and other forms of oppression may help explain these inequities.

OBJECTIVES

To describe the application of real-time data collection using ecological momentary assessment (EMA) and smartphone technology to assess exposure to stress, racism, sexism, microaggressions, and other forms of oppression.

METHODS

The Postpartum Mothers Mobile Study (PMOMS) is an ongoing longitudinal cohort study that began recruitment in December 2017. Participants delivering at a hospital in Pittsburgh, PA are recruited by 29 weeks' gestation. Using smartphones and smart scales, participants complete daily surveys related to psychosocial, behavioural, and contextual factors and weigh themselves weekly for approximately 15 months. We provide a preliminary descriptive analysis of EMA self-reported measures of stress, racism, sexism, and microaggressions; and non-EMA measures of stress and major discrimination.

RESULTS

The sample (n = 230) is 63.5% White, 24.8% Black/African American, and 7% Hispanic origin. The most commonly reported item from the Major Discrimination Scale is being unfairly fired (18.1% of the sample). Of those, 31.7% and 17.1% attribute unfair firing to their gender and race, respectively. From the random EMA measures, on average, participants report experiences of racism and sexism at least once daily, in an average 12-hour day over the 4-week period. Black participants indicate about two experiences per day of racism, and White participants indicate more than 1 per day of sexism. Mean stress levels from the EMA measures were similar to the stress measures collected at baseline.

CONCLUSIONS

The methods applied in PMOMS provide real-time data regarding how participants' daily experiences of stress and discrimination influence their lives. Future work will include understanding if and how these EMA measures may relate to already established measures of racism, sexism, and stress; and ultimately understanding associations with perinatal inequities.

Maternal pre and perinatal experiences with their full-term, preterm and very preterm newborns

Background

Mothers’ reports about pregnancy, maternity and their experiences during the perinatal period have been associated with infants’ later quality of attachment and development. Yet, there has been little research with mothers of very preterm newborns. This study aimed to explore mothers’ experiences related to pregnancy, premature birth, relationship with the newborn, and future perspectives, and to compare them in the context of distinct infants’ at-birth-risk conditions.

Methods

A semi-structured interview was conducted with women after birth, within the first 72 h of the newborn’s life. A total of 150 women participated and were divided in three groups: (1) 50 mothers of full-term newborns (Gestational Age (GA) ≥ 37 weeks; FT), (2) 50 mothers of preterm newborns (GA 32–36 weeks; PT) and (3) 50 mothers of very preterm newborns (GA < 32 weeks; VPT).

Results

Mothers of full-term infants responded more often that their children were calm and that they did not expect difficulties in taking care of and providing for the baby. Mothers of preterm newborns although having planned and accepted well the pregnancy (with no mixed or ambivalent feelings about it) and while being optimistic about their competence to take care of the baby, mentioned feeling frightened because of the unexpected occurrence of a premature birth and its associated risks. Mothers of very preterm newborns reported more negative and distressful feelings while showing more difficulties in anticipating the experience of caring for their babies.

Conclusion

The results indicate that Health Care Systems and Neonatal Care Policy should provide differentiated psychological support and responses to mothers, babies and families, taking into account the newborns’ GA and neonatal risk factors.

Research priorities of women at risk for preterm birth: findings and a call to action

BACKGROUND

Traditional hierarchical approaches to research give privilege to small groups with decision-making power, without direct input from those with lived experience of illness who bear the burden of disease. A Research Justice framework values the expertise of patients and communities as well as their power in creating knowledge and in decisions about what research is conducted. Preterm birth has persisted at epidemic levels in the United States for decades and disproportionately affects women of color, especially Black women. Women of color have not been included in setting the agenda regarding preterm birth research.

METHODS

We used the Research Priorities of Affected Communities protocol to elicit and prioritize potential research questions and topics directly from women of color living in three communities that experience disproportionately high rates of preterm birth. Women participated in two focus group sessions, first describing their healthcare experiences and generating lists of uncertainties about their health and/or healthcare during pregnancy. Women then participated in consensus activities to achieve 'top-priority' research questions and topic lists. The priority research questions and topics produced by each group were examined within and across the three regions for similarities and differences.

RESULTS

Fifty-four women participated in seven groups (14 sessions) and generated 375 researchable questions, clustered within 22 topics and four overarching themes: Maternal Health and Care Before, During, and After Pregnancy; Newborn Health and Care of the Preterm Baby; Understanding Stress and Interventions to Prevent or Reduce Stress; and Interpersonal and Structural Health Inequities. The questions and topics represent a wide range of research domains, from basic science, translational, clinical, health and social care delivery to policy and economic research. There were many similarities and some unique differences in the questions, topics and priorities across the regions.

CONCLUSIONS

These findings can be used to design and fund research addressing unanswered questions that matter most to women at high risk for preterm birth. Investigators and funders are strongly encouraged to incorporate women at the front lines of the preterm birth epidemic in research design and funding decisions, and more broadly, to advance methods to deepen healthcare research partnerships with affected communities.

Research priorities of women at risk for preterm birth: findings and a call to action

Background

Traditional hierarchical approaches to research give privilege to small groups with decision-making power, without direct input from those with lived experience of illness who bear the burden of disease. A Research Justice framework values the expertise of patients and communities as well as their power in creating knowledge and in decisions about what research is conducted. Preterm birth has persisted at epidemic levels in the United States for decades and disproportionately affects women of color, especially Black women. Women of color have not been included in setting the agenda regarding preterm birth research.

Methods

We used the Research Priorities of Affected Communities protocol to elicit and prioritize potential research questions and topics directly from women of color living in three communities that experience disproportionately high rates of preterm birth. Women participated in two focus group sessions, first describing their healthcare experiences and generating lists of uncertainties about their health and/or healthcare during pregnancy. Women then participated in consensus activities to achieve ‘top-priority’ research questions and topic lists. The priority research questions and topics produced by each group were examined within and across the three regions for similarities and differences.

Results

Fifty-four women participated in seven groups (14 sessions) and generated 375 researchable questions, clustered within 22 topics and four overarching themes: Maternal Health and Care Before, During, and After Pregnancy; Newborn Health and Care of the Preterm Baby; Understanding Stress and Interventions to Prevent or Reduce Stress; and Interpersonal and Structural Health Inequities. The questions and topics represent a wide range of research domains, from basic science, translational, clinical, health and social care delivery to policy and economic research. There were many similarities and some unique differences in the questions, topics and priorities across the regions.

Conclusions

These findings can be used to design and fund research addressing unanswered questions that matter most to women at high risk for preterm birth. Investigators and funders are strongly encouraged to incorporate women at the front lines of the preterm birth epidemic in research design and funding decisions, and more broadly, to advance methods to deepen healthcare research partnerships with affected communities.