Maternal health outcomes differ significantly between racial groups within the United States. The American College of Obstetricians and Gynecologists describes these disparities in obstetric outcomes as "prevalent and persistent." Black, indigenous, and people of color are disproportionately affected by many of the maternal health outcomes listed as national objectives in the U.S. Department of Health and Human Services's national health objectives program, Healthy People 2030. The American Public Health Association considers maternal mortality to be a human rights issue, also noting the disparate rates of Black maternal death. Race affects maternal health throughout the pregnancy continuum, beginning prior to conception and continuing through pregnancy (antepartum), during labor and childbirth (intrapartum), and after birth (postpartum).
There are multiple explanations for racial disparities in maternal health. Biological factors, such as higher rates of preexisting chronic disease prior to pregnancy, fail to fully account for differences in outcomes. There is a lack of evidence to support a genetic difference between racial groups as a cause of maternal health disparities such as preterm birth. Social factors, such as structural racism, have been suggested as a contributory cause of the wide racial disparities in maternal health in the United States. Experiences of racism and discrimination may also contribute to hypertension indirectly through stress on the pregnant individual. Disparities in adverse pregnancy outcomes for Black women have been hypothesized to be related to higher loads of allostatic stress before and during pregnancy, epigenetic changes, and/or telomere shortening. Studies of potential biomarkers of allostatic stress have failed to date to demonstrate the racial group differences seen with self-report measures. Inequities in access and the provision of health care may also effect maternal outcomes. The effects of implicit and explicit provider bias in obstetrical care has been poorly studied and may contribute to disparate outcomes. The information health care providers share and how that information is presented affects the autonomy and decision-making of birthing women.
Proposed interventions to reduce racial disparities in maternal health outcomes target changes at individual, health care system, and health care policy levels. Some states are utilizing federal block grant money for initiatives targeting reductions in maternal morbidity and mortality for Black and Hispanic women. Efforts have been made to address racial inequalities for birthing women by providing continuing education for healthcare providers. Measurement, methodological, and ethical issues arise when using race in health outcomes research. Recommendations for appropriate use of race as a research variable may limit use of white normative standards in the future, which can imply non-white people as being atypical. Proposed alternative variables for race may be genetic ancestry, socioeconomic factors, or differential opportunities.
Preconception
Unintended pregnancy Overall, approximately 50% of pregnancies in the United States are unplanned, however Black and Hispanic women are more likely to have unplanned pregnancy than white women. Unintended pregnancies are associated with increased risk of delayed entry into prenatal care, decreased rates of breastfeeding after birth, increased risk of maternal depression, and increased risk of domestic abuse. The cost of unintended pregnancy in the United States exceeded $20 billion in 2010.
Social determinants of health
Environment While limited research is available about the reproductive system effects of environmental pollutants, evidence from animal models indicates risks to humans. Black families are more likely to live in neighborhoods with poorer air quality and higher rates of heavy metal contaminants. Air pollution has been associated with increased risk of preterm birth. Heavy metals such as lead and mercury are known neurotoxins and the developing fetal nervous system may be particularly vulnerable to excessive levels. Exposure to organic pollutants prior to conception is linked to lower birth weight in infants. One study of pesticide use in New York found the highest rate of exposure in Black women; pesticide exposure in pregnancy is associated with low birth weight and smaller head circumference. The correlation between pesticide and pollutants on fetal growth restriction seen in Black women in New York City was not demonstrated among Dominican women living in the same neighborhoods, suggesting there may be a cultural modifier.
Economic status Strategies to improve pregnancy outcomes through behavioral interventions like folic acid supplementation and smoking cessation may be too little too late, as many women enter prenatal care several weeks into sensitive fetal development. Optimizing preconception health is recommended by several professional organizations to optimize maternal health prior to pregnancy, particularly for women with chronic diseases. Low income women, however, are less likely to have access to preconception and preventive health care. In general, financial disadvantages heavily impact an expecting mother’s risk for adverse outcomes at birth. Racial disparities in poverty adversely effect Black and Hispanic families.
Chronic health conditions Chronic hypertension prior to and during pregnancy is associated with increased risk of preeclampsia, eclampsia, placental abruption, stroke, cardiomyopathy, heart failure, pulmonary edema, renal failure, and maternal death. Black women are more than twice as likely as white women to be diagnosed with chronic hypertension. Black, Asian, and Pacific Islander women are more likely to have chronic hypertension that necessitates preterm delivery than white women.
While less than 1% of births in the United States are effected by preexisting maternal diabetes, uncontrolled glycemic levels prior to and during pregnancy are associated with increased risk of congenital anomalies, preeclampsia, macrosomia, Cesarean birth, preterm birth, and stillbirth. Even after adjusting for risk factors such as smoking, socioeconomic status, years of education, and body mass index (BMI), Black and Hispanic people have higher risk of developing diabetes than their white counterparts. Asian people are also at higher risk of diabetes compared to white people, and subgroup analysis indicates that those who identify as South Asian (Indian, Pakistani, Sri Lankan, Bangladeshi, Nepali, or Bhutanese) have the highest prevalence of diabetes. Evidence also suggests that Hispanic and Asian people are more likely to have undiagnosed diabetes and that Asian people are more likely to be diagnosed with diabetes at lower BMIs than other racial groups.
Samoan, Hawaiian, Native American, Alaskan Native, Black, Mexican, Puerto Rican, Central American, and South American women are at higher risk of pre-pregnancy obesity. Women with BMI greater than 40 during pregnancy are at increased risk for fetal cardiac defects and comorbidities such as hypertension, hyperlipidemia, and obstructive sleep apnea.
Antepartum
Prenatal care Black, Hispanic and Native American women are more likely to have late entry to prenatal care than white women. One study found that Asian women under the age of 18 years old were the most likely to start prenatal care after the first trimester. Black women are more likely to have less than five prenatal visits, which is associated with increased risk of maternal mortality. Late entry to prenatal care and inadequate prenatal care are associated with increased likelihood of preterm birth, increased risk of low birthweight infants, and increased infant mortality. Many of the quality measures included in indices of prenatal care lack established correlations to improved maternal health outcomes.
Black, Hispanic and Native American women are more likely to report site-related barriers to receiving prenatal care, such as distance to the clinic and lack of transportation to appointments. Black women are also more likely to report inconvenience as a barrier to care, such as longer appointment wait times.
Pregnancy loss Early pregnancy loss, miscarriage before the end of the 20th week of gestation, occurs in approximately 10-15% of all clinically confirmed pregnancies. Racial differences in miscarriages between Black and white women are not seen in early pregnancy prior to 10 weeks estimated gestational age, however Black women are almost twice as likely as white women to experience pregnancy loss between 10 and 20 weeks estimated gestational age. The Weathering Hypothesis, first described by Arline Geronimus, has been proposed as the neuroendocrine immune pathway by which Black women experience this higher rate of early pregnancy loss.
Racial disparities in pregnancy loss after the completion of 20 weeks of gestation, or stillbirth, have been documented in the United States since at least as early as 1918. Despite an overall decreasing rate of stillbirth nationally, Black women remain twice as likely as white women to experience fetal death. This disparity persists after adjusting for sociodemographic and maternal health factors, suggesting that social factors, such as housing segregation, may play a role. Stillbirth risks for Hispanic, Native American, and Alaskan Native women are higher than for white women, although not to the same extent as Black women. Asian and Pacific Islander women have approximately the same risk of stillbirth as white women.
Medical conditions in pregnancy Black women are more likely than white women to have anemia during pregnancy, which has been associated with low birth weight infants, preterm birth, or both in some studies. Racial disparities in incidence of anemia in pregnancy persist across socioeconomic groups.
Asian women are more likely to be diagnosed with gestational diabetes during pregnancy than white women, regardless of BMI. Studies of gestational diabetes often fail to distinguish between subgroups of Asian women or differentiate Pacific Islander women, however one study found that while Pacific Islander women were at increased risk of gestational diabetes compared to white women, their risk was less than that of Asian women. While racial and ethnic groups including Hispanic, Native American, African, and Australian Aboriginal women are often reported to be at increased risk of developing gestational diabetes, racial disparities could be succinctly summarized as increased risk for women who identify as non-white.
Black women are at increased risk of preeclampsia, a finding that is not fully explained by the increased incidence of chronic hypertension in that population. Compared to other racial groups, Black women are also more likely to have serious complications of pre-eclampsia such as eclampsia, stroke, acute heart failure, pulmonary edema, and renal failure. The increased incidence of preeclampsia in Black women seems to have a social or cultural component, as Black women born outside the United States and residing within the US for less than 10 years have a significantly less likelihood of developing pre-eclampsia than Black women born and living in the US. After more than 10 years of living in the US this group difference based on place of birth is not significant. Black women with preeclampsia are also more likely to have stillbirth than similar white women, while Hispanic women with preeclampsia do not have increased risk compared to similar white women.
Intrapartum
Preterm birth