Dr. Paula Braveman's tipping point was when a patient at her community clinic in San Francisco's Mission District, slipped past her front desk and knocked on her door to say goodbye. He told her he couldn't afford to go to the clinic any more and he wouldn't be coming back.

Braveman was at a turning point when she realized that her goal was not just to heal the sick but to also advocate for policies that would make them healthier. Braveman has been studying "social determinants" of health for nearly 40 years. These are the places where we live, learn, play, and work and the relationships that we have there. This is how we become healthy.

Braveman is the director of the Center on Social Disparities in Health, University of California-San Francisco. She has researched the relationship between neighborhood wealth and children’s health and how prenatal care can be affected by insurance access. She is a long-standing advocate for translating research into policy and has worked with the San Francisco health department, the federal Centers for Disease Control and Prevention, and the World Health Organization on major health initiatives.

Braveman is particularly interested in infant and maternal health. Braveman's latest research examines the evidence regarding the persisting gap in preterm birth rates in America between Black and White women. Black women are nearly 1.6 times more likely than whites to have a baby three weeks or more before their due date. This statistic has serious and expensive health implications. Premature babies are more likely to have breathing problems, brain abnormalities, and heart disease.

Braveman was co-author of the review along with a group of experts assembled by the March of Dimes, which included geneticists and clinicians as well as epidemiologists, biomedical specialists, neurologists, and biomedical experts. The review examined over two dozen possible causes of preterm births. They also looked at quality of prenatal care and environmental toxicities.

Note: The authors use the terms "upstream", "downstream" extensively in the review to describe the factors that affect people's health. A downstream risk refers to the condition or factor that is most directly responsible for an outcome in health. An upstream factor, on the other hand, is what causes or fuels the downstream danger -- and what must be done to avoid someone becoming sick. A person who lives near water contaminated with toxic chemicals could get sick by drinking it. A downstream solution would be to tell people to use filters. Stopping the dumping toxic chemicals would be an upstream solution.

KHN interviewed Braveman about the study's findings. These excerpts have been edited to improve style and length.

Q: How long have you been researching the topic of preterm births and racial disparities? Did you find any surprising results from the review?

It was a systematic process of going through all the risk factors mentioned in literature, and then looking at how racism was an upstream determinant of almost all of them. It was quite amazing.

Another thing that was impressive was the possibility that preterm birth disparities could be caused by genetic factors. There were at most three to four genetics experts in this group. They concluded that genetic factors could influence preterm birth disparities, but the effect would only be small. This cannot explain the higher rate of preterm birth in Black women than white women.

Q: I was trying to find out not only what causes preterm labor, but also how to explain the racial disparities in preterm birth rates. Is there a way to explain racial disparities in preterm birth?

Although it does appear that preterm birth may have genetic components, they do not explain the Black-white gap in preterm birth. An example of this is an elective C-section performed early. This is one problem that can lead to preterm births, but it doesn’t seem to be contributing to the Black-white disparity.

Q: Your colleagues and you have identified racism as the primary cause of preterm birth. What would you say about the certainty that preterm birth rates are higher among Black women because of racism?

This makes me think about this saying: A randomised clinical trial would not be necessary to establish the importance of a parachute if you are able to jump from a plane. It seems close.

Looking through the paper, I can't believe that the evidence we have is not possible to explain. We worked on it for three or four years.

Q: What can a mother's wider lifetime experiences of racism affect her birth outcomes? How does this compare to what she has experienced in the medical establishment during her pregnancy?

Although there are many ways in which racial discrimination could affect a woman’s pregnancy, one of the most important would be through stress-related biological mechanisms and pathways. It has been proven that chronic stressors are more harmful to your health than acute stressors in neuroscience.

It doesn't make sense to focus on pregnancy only. That's the main focus of most research: pregnancy stress and racial discrimination and their role in birth outcomes. Few studies have examined the effects of racial discrimination on individuals throughout their lives.

My colleagues and me published a paper in which we asked African American women their experiences with racism. We didn't even know what that meant. The experiences of racism in pregnancy were not something women talked about with their doctors. Instead, they spoke about their lifetime experiences and especially those from childhood. They talked about the need to be vigilant and worry so that they are prepared for any incident.

All of this combined with the knowledge we have about stress physiology would lead me to believe that lifetime experiences are more valuable than those during pregnancy. Preterm birth is not well understood. However, what we do know is that inflammation and immune dysfunction are involved. This is what stress can lead to. Neuroscientists have demonstrated that chronic stress can cause inflammation and immune system dysfunction.

Q: Which policies are you most concerned about at this point in order to reduce preterm births for Black women?

Although I wish I could only say one or two policies at a time, I believe it all comes back to the need for eradicating racism from our society. All of it. It's not possible to simply say "Oh, here is my magic bullet." That will solve your problem if you just do that.

You can't just focus on the downstream factors if you consider the findings of this study. It is up to the upstream to make society more fair and less racist. Let's face it, that's what I believe is the main take-home. It's a huge task.