Socioeconomic and ethnic inequality are primary drivers of stillbirths, preterm births, and births with fetal growth restriction (FGR) in England, with the largest disparities seen among socioeconomically deprived Black and South Asian women, according to results from a national cohort study published in The Lancet.
In many high-income nations, women in socioeconomically disadvantaged and minority ethnic groups tend to face worse pregnancy outcomes compared to White women and those who are better off financially, experiencing higher rates of stillbirth, preterm births, FGR, and neonatal and infant mortality. However, while health policies in many of these countries have prioritized tackling such disparities, such efforts are impeded by “a paucity of information about how these inequalities are related to women’s societal circumstances and pre-existing health and which groups are most strongly affected,” Jennifer Jardine, PhD, of the Royal College of Obstetricians and Gynecologists in London, and colleagues from the National Maternity and Perinatal Audit Project Team explained.
In order to help develop a better understanding of inequalities in pregnancy outcomes in the U.K., Jardine and colleagues conducted a national cohort study using data from the 2019 National Maternity and Perinatal Audit report to quantify socioeconomic and ethnic disparities in stillbirths, preterm birth, and FGR in England while taking into account patient health at pregnancy onset and complications that arose over the course of the pregnancy.
“In this study of more than 1 million births in England, 24% of stillbirths, 19% of preterm livebirths, and 31% of livebirths with FGR would not have occurred if all women had the same risk of adverse pregnancy outcomes as women in the least deprived socioeconomic group,” Jardine and colleagues found. “These population attributable fractions were considerably lower when adjusted for ethnicity, maternal smoking, and BMI at the onset of pregnancy, which suggests that much of the socioeconomic inequalities in pregnancy outcomes can be explained by the combined influences of these maternal characteristics.”
What’s more, 12% of stillbirths, 1% of preterm births, and 17% of births with FGR would not have occurred at all if each woman had the same risks as White women, the study authors noted. “Adjustment for socioeconomic deprivation, maternal smoking, and BMI had little effect on these population attributable fractions,” they added.
For their analysis, the study authors included all women in the National Maternity and Perinatal Audit dataset who gave birth to a singleton baby with a recorded gestation between 24 and 42 completed weeks, if information was available on whether the baby was born alive or stillborn. They assessed data on stillbirths, preterm birth (<37 weeks’ gestation), and FGR (liveborn of at least 24 weeks’ gestation with birth weight below the 3rd centile for gestational age according to UK-WHO growth charts) and compared these outcomes by socioeconomic deprivation quintile (determined using the Index of Multiple Deprivation) and ethnic group.
The study authors calculated population attributable risk fractions—which indicate the proportion of a particular outcome that would be removed if a risk factor did not exist or was more similar to a reference population—for the entire population and specific groups compared with women in the least socioeconomically deprived quintile or White women, both unadjusted and with adjustment for smoking, body mass index (BMI), and other risk factors.
They ultimately identified 1,155,981 women with a singleton birth between April 1, 2015-March 31, 2017, who met the study criteria. Of these, 4,505 (0.4%) were still births; of the remaining 1,151,476 livebirths, 69,175 (6.0%) were preterm births and 22,679 (2.0%) were births with FGR.
“Risk of stillbirth was 0.3% in the least socioeconomically deprived group and 0.5% in the most deprived group (P<0.0001), risk of a preterm birth was 4.9% in the least deprived group and 7.2% in the most deprived group (P<0.0001), and risk of FGR was 1.2% in the least deprived group and 2.2% in the most deprived group (P<0.0001),” Jardine and colleagues found. “Population attributable fractions indicated that 23.6% (95% CI 16.7–29.8) of stillbirths, 18.5% (16.9–20.2) of preterm births, and 31.1% (28.3–33.8) of births with FGR could be attributed to socioeconomic inequality, and these fractions were substantially reduced when adjusted for ethnic group, smoking, and BMI (11.6% for stillbirths, 11.9% for preterm births, and 16.4% for births with FGR).”
When it came to ethnic disparities, they found that “risk of stillbirth ranged from 0.3% in White women to 0.7% in Black women (P<0.0001); risk of preterm birth was 6.0% in White women, 6.5% in South Asian women, and 6.6% in Black women (P<0.0001); and risk of FGR ranged from 1.4% in White women to 3.5% in South Asian women (P<0.0001). 11.7% of stillbirths (95% CI 9.8–13.5), 1.2% of preterm births (0.8–1.6), and 16.9% of FGR (16.1–17.8) could be attributed to ethnic inequality.”
Unlike with socioeconomic inequality, adjusting for socioeconomic deprivation, smoking, and BMI only had a small effect on ethnic group attributable fractions (13.0% for stillbirths, 2.6% for preterm births, and 19.2% for births with FGR). And, they added, “Group-specific attributable fractions were especially high in the most socioeconomically deprived South Asian women and Black women for stillbirth (53.5% in South Asian women and 63.7% in Black women) and FGR (71.7% in South Asian women and 55.0% in Black women).”
“The stark reality is that across England, women’s socioeconomic and ethnic background are still strongly related to their likelihood of experiencing serious adverse outcomes for their baby. I think that people will be shocked to see that these inequalities are still responsible for a substantial proportion of adverse pregnancy outcomes in England,” Jardine said in a press release on the results.
These findings from Jardine and colleagues suggest “that large-scale action is needed to reduce disparities in birth outcomes,” wrote Jessica L. Gleason, PhD, MPH, and Katherine L. Grantz, MD, MS, both of the Eunice Kennedy Shriver National Institute of Child Health and Human Development at the U.S. National Institutes of Health in Bethesda, Maryland, in a commentary accompanying the study.
Moreover, the evidence also “emphasizes that individual-level targeting of risk factors will probably continue to lead to incremental change that has little impact on population-level metrics,” Gleason and Grantz added. “Jardine and colleagues demonstrate this by adjusting for individual risk factors in their analyses, reporting that none of the outcomes could be fully attributed to individual-level maternal characteristics, and that the proportions of stillbirth and fetal growth restriction did not change after these adjustments. Although adjustment for body-mass index and smoking did reduce the population attributable fractions in many cases, intervention at the point of prenatal care could help the individual but do little to affect population health.”
Similarly, Jardine and colleagues explained that increased rates of adverse outcomes in pregnancy among ethnic minority groups “are not explained by socioeconomic deprivation alone. Other factors related to discrimination based on race, religion, and culture can contribute to a societal disadvantage and increase the risk of poor pregnancy outcomes. In addition, physiological differences between ethnic groups might lead to differences in maternal immunological, vascular, and endocrine responses. All this indicates that more detailed causal mediation analysis is a research priority.”
In order to ensure that such disparities are properly addressed and improve outcomes, the study authors argued that attempts to address inequality in pregnancy outcomes “will have to move from addressing the downstream factors such as specific clinical conditions and lifestyle factors, to the conditions that ultimately influence the choices that individuals can make about their own lives. These upstream factors include access to high-quality education, employment, and fairness in terms of income and welfare support. As risk is spread across the whole population, interventions must address the whole population to achieve their maximum benefit.”
Gleason and Grantz agreed, arguing that targeting individual-level risk factors “has little impact on the incidence of poor birth outcomes in the population. It is therefore crucial to develop population-level solutions to change rates of adverse birth outcomes on a national level.”
And such efforts are needed on a global scale, including in the U.S. According to a CDC report published in Morbidity and Mortality Weekly Report (MMWR) in September, Black, American Indian, and Alaska Native (AI/AN) women are two to three times more likely to die from pregnancy-related causes than White women. That disparity increased with age, the CDC noted, with pregnancy-related mortality among Black and AI/AN women older than 30 years four to five times as high as for White women of the same age group.
A previous CDC report using data from several U.S. state Maternal Mortality Review Committees (MMRCs) found that “each pregnancy-related death was associated with several contributing factors, including access to appropriate and high-quality care, missed or delayed diagnoses, and lack of knowledge among patients and providers around warning signs,” the CDC explained. “MMRC data suggest the majority of deaths—60% or more—could have been prevented by addressing these factors at multiple levels.”
“Concerted action is needed to reduce inequalities in pregnancy outcomes,” Jardine and colleagues concluded. “Maternity services and public health professionals should work closely with politicians to address the full complexity of the pathways that contribute to the socioeconomic and ethnic differences in pregnancy outcomes, targeting the entire population and those groups at the highest risk.”
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Socioeconomic and ethnic disparities led to a higher incidence of stillbirths, preterm births, and births with fetal growth restriction (FGR) among pregnant women in England, with socioeconomically deprived Black and South Asian women experiencing the worst pregnancy outcomes.
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Study findings suggest that a substantial number of stillbirths, preterm births, and births with FGR would not have occurred if all women had the same risk of adverse pregnancy outcomes as more socioeconomically advantaged or White women.
John McKenna, Associate Editor, BreakingMED™
All study authors declared funding from the Healthcare Quality Improvement Partnership to deliver the National Maternity and Perinatal Audit Program. No other relevant relationships were disclosed.
Gleason and Grantz had no relevant relationships to disclose.
Cat ID: 41
Topic ID: 83,41,585,730,41,192,925
