By Jason Jarzembowski, MD, PhD

One of the largest health crises in the United States is the high infant mortality rate, which exceeds that of many European nations we consider economic and political peers. The state of Wisconsin and the city of Milwaukee are no exception to this trend, with an even worse gap between the survival of black infants and white infants. This survival gap is termed a health inequity which is defined by the World Health Organization as a systematic difference in a health outcome between different population groups.

According to 2012-2015 data from the City of Milwaukee’s Fetal and Infant Mortality Review (FIMR) Committee, the white infant mortality rate was 4.9 per 1,000 births, while the black infant mortality rate was three times higher at 14.9 per 1,000 births. Additionally, the stillbirth rate was twice as high for African-American mothers: 9.7 versus 4.2 per 1,000 births.

Although infant mortality rates have dropped over the past decade, this gap has persisted. The difference in infant outcomes between black and white women is mostly the result of increased rates of preterm and low birthweight infants. These babies are at much higher risk for death or health complications before, during and after delivery.

Many factors contribute to the disproportionately high black infant mortality rate. The earliest explanation suggested was socioeconomic; women with financial, housing or insurance issues had worse pregnancy outcomes, and perhaps more black women were in that category. However, data quickly showed that this did not explain the difference.

At every income level, black women had higher infant mortality than white women. Even wealthy, professional black women have higher rates of pregnancy complications and infant mortality than their white counterparts. These findings show that factors besides poverty and limited access to health care must account for the racial inequity.

Another potential factor considered was genetics. Some diseases, such as sickle cell disease, are more common among black persons than white persons. However, this is actually an ethnic difference, where ethnicity is defined by the American Sociological Association as “shared culture, such as language, ancestry, practices, and beliefs.” Race, on the other hand, is based on “physical differences that groups and cultures consider socially significant.”

The sickle cell trait provides protection against malaria and is more common among persons of Middle Eastern, Indian, Mediterranean and African descent where malaria is more prevalent, but not in populations from other geographic areas who have different ethnicity but might still be considered racially black. In the United States, the racial group of black mothers is ethnically diverse, and known and unknown genetic differences within the ethnic groups cannot by themselves account for the worse pregnancy outcomes seen across this group as a whole. Furthermore, researchers Richard David and James Collins found when black women immigrate to the U.S., they at first have pregnancy outcomes similar to white women, but over the next generation or two, their infants fare worse and the inequity appears. This suggests that social and environmental factors, which change when someone relocates, are more important that genetic factors, which remain constant across someone’s lifetime.

Over the past decade or so, a novel explanation has arisen: chronic stress. We know that chronic stress – due to difficult living or working conditions, adverse social situations, poor nutrition or lack of sleep – can cause detectable physical changes. When the body’s stress hormones rise, the immune system activates and prepares for “fight or flight.” In the short term, this is a helpful response. The sudden burst of alertness you feel when you’re startled helps you react in the moment and it subsides when the situation is over.  But if this heightened state persists over the long term, it can have harmful effects. Chronic stress can lead to weight gain, high blood pressure and an increased risk of many other diseases. It can also worsen existing conditions and impair the ability to heal.

Black women may experience more chronic stress for many reasons, but perhaps the most important and least easily measured is racism. This explanation fits with the uniquely poor pregnancy outcomes of African-American women compared to white, Asian or Hispanic women. It would explain why even wealthy and professionally successful black women have higher infant mortality than their similarly well-off white colleagues. It would also explain why older black women are at higher risk than younger ones – they’ve had more years for the effects of stress to accumulate. (This is in stark contrast to white women, where teenage mothers have worse outcomes than those in their 20s and 30s.)

Chronic stress may adversely affect mothers and babies in several ways. First, stressed black mothers are more likely to develop conditions like high blood pressure during pregnancy, which increases the risk of low birth weight infants, preterm delivery and maternal complications. Second, they are more likely to have more severe diseases with more complications. Finally, health care providers may consciously or unconsciously, with good or bad intentions, treat black mothers differently.

After delivering her baby, Serena Williams, the professional tennis player, developed a blood clot in her lungs that was undiagnosed as her symptoms and concerns went unaddressed. This is not a rare story – many medical studies have shown that black men and women receive less aggressive treatment or no treatment more often than their white counterparts. Thus, a group of women who are more likely to have health problems and who are more likely to have more severe courses of those diseases, are also more likely to be undertreated.

So what can be done to address this racial disparity in infant mortality? The best long-term solution involves eliminating the chronic stress of all black women by confronting racism and inequality – but this will be difficult and lengthy work. In the short term, we can better educate African-American women and their health care providers to raise awareness of these issues, we can individualize their care using nurses, doulas or midwives to provide personalized monitoring and treatment, and we can continue research into this tragic gap in order to improve the health of African-American women and their babies.


American Sociological Association (2018). Race and ethnicity. Retrieved from

Collins, James & David, Richard (2007). Disparities in Infant Mortality. American Journal of Public Health.

The RACE Project: American Anthropology Association (2016). Health connections: Do genes determine our health?  Retrieved from

World Health Organization (2017). 10 facts on health inequities and their causes. Retrieved from