Study Finds Site of Delivery Contributes to Racial and Ethnic Disparities in Pregnancy-related Severe Maternal Morbidity

A recent study examining the impact of hospital quality on racial and ethnic disparities in pregnancy-related morbidity in New York City found that differences in the hospitals where Black and White women deliver contribute to the disparity in severe maternal morbidity rates. According to the NIMHD-funded study, severe maternal morbidity (a life-threatening diagnosis or life-saving procedure during delivery hospitalization) was more common among Black women than among White women, and Black mothers were more likely to deliver at hospitals with higher risk-adjusted rates of severe maternal morbidity. The study estimated that differences in delivery location may contribute as much as 47.7 percent of the racial disparity in severe maternal morbidity rates in New York City.

For every maternal death, 100 women experience severe maternal morbidity, such as a life-threatening diagnosis like renal failure or a complication that requires a life-saving procedure such as a hysterectomy or blood transfusion, during delivery. Data suggest that half of maternal deaths and severe events are preventable, according to the study’s principal investigator, Dr. Elizabeth Howell, Professor and Vice Chair of Research for the Department of Obstetrics, Gynecology, and Reproductive Science, and Professor of Population Health Science and Policy at the Icahn School of Medicine at Mount Sinai in New York.

Dr. Elizabeth Howell

“There is a persistent and longstanding Black-White disparity in maternal mortality in the U.S., and it is particularly persistent and prevalent in specific areas like New York City,” said Dr. Howell. “Black women are 12 times more likely to die in pregnancy than White women in New York City. It was eight times as likely just five to six years ago. This is three to four times greater than the Black-White maternal mortality disparity in the U.S. What is striking is the gap. One half of these events are preventable through patient, provider, and system factors, which suggests that hospital quality really matters. We also need to look at access to care, education, and antenatal care among patients.”

Researchers linked birth records with maternal discharge information to identify cases of severe maternal morbidity during deliveries and to examine Black-White differences in rates of severe maternal morbidity in New York City hospitals. The team then analyzed the risks of severe maternal morbidity for Black and White women for each hospital and assessed differences in the distributions of Black and White deliveries among these hospitals. The analyses factored in patient characteristics, comorbidities, and other criteria to determine risk-adjusted rates of maternal morbidity for each hospital. Hospitals were ranked from lowest to highest risk-standardized rates of severe maternal morbidity.

Results indicate that racial differences in the distribution of deliveries may contribute to the Black-White disparity in severe maternal morbidity rates in New York City hospitals. Severe maternal morbidity rates were higher among Black women (4.2 percent) than among White women (1.5 percent), and risk-adjusted severe morbidity rates among hospitals ranged from 0.8 percent to 5.7 percent for every 100 deliveries. Black women were much less likely to deliver in lowest risk-adjusted hospitals and more likely to deliver in hospitals with higher rates of maternal morbidity: Just 23 percent of Black women’s deliveries were in hospitals with the lowest morbidity rates, compared with 65 percent of deliveries to White women.

“In our previous work looking at national data, we found that Black women deliver in a concentrated set of hospitals, and these hospitals have higher risk-adjusted severe maternal morbidity rates,” said Dr. Howell. “But the wide variation in hospital performance and the extent to which Black and White women deliver in different hospitals in New York City was surprising.”

For the next phase of the study, researchers are examining maternal morbidity disparities among all racial and ethnic groups in New York City hospitals, focusing first on Hispanic/Latino women. In an effort to improve overall quality in New York City hospitals and reduce rates of maternal morbidity for all women, the researchers are also conducting qualitative interviews to find out why there is such wide variation in the quality of care among hospitals and why disparities in maternal morbidity exist. For example, the researchers are conducting focus groups with mothers to look at barriers to receiving care and factors in mothers’ decisions about where to deliver.

“We think this is really important work,” said Dr. Howell. “If we can share what we learn with hospitals that are not performing as well, we can narrow the Black-White morbidity gap and reduce disparities, improve quality, and reduce severe maternal morbidity rates in New York City.”


  1. Howell EA, Egorova NN, Balbierz A, Zeitlin J, Hebert PL. Site of delivery contribution to black-white severe maternal morbidity disparity. Am J Obstet Gynecol. 2016; 215: 143-152.

Posted March 3, 2017