MM: Very few people start their careers with the idea of becoming an epidemiologist. What was your path to becoming an epidemiologist?
CH: It was like that, actually. When I was in high school, I did a research article on the population explosion, which was very much a concern in the early 60s. And I decided that really was what I needed to spend my career looking at and trying to affect, because of the big impact that population has on environment and everything else, including violence and so on. I went to college with that in mind, majored in sociology with a minor in psychology, and when it was time to go to graduate school, I had a National Science Foundation Fellowship to go to a university that had a population center. I chose the Carolina Population Center and to go into the Department of Sociology. So at that point, I was on target to go into sociology and to study to be a demographer. But I had deferred my admission for a year so that my husband could finish up his work and join the faculty at North Carolina State. So we visited North Carolina State and the University of North Carolina in the spring, and the head of the Department of Sociology says, “Well, there’s no problem with the deferred admission, you would be coming in the fall, but we look at the income of husbands when we consider the fellowships for wives.” I said, “Well, do you consider the income of wives when you look for fellowships for husbands?” (having just put my husband through 3 years of graduate school). He said no, he had never thought of that. What he didn’t understand was that I had this fellowship already, but I thought this is not the place for me. And I went back to where we were living in Knoxville and called my friend who was head of Planned Parenthood, and I said that I really need to know how to link in with the Carolina Population Center at the University of North Carolina without being in the Department of Sociology. She said, “Well it turns out that Russ Richardson, who is the regional head of Planned Parenthood, is doing a Ford Midcareer Fellowship at the University of North Carolina, you should and ask him.” So I did, and he said, “I’m in the Department of Maternal and Child Health at the School of Public Health, and it is connected to the Carolina Population Center, so why don’t you apply to transfer to get a Masters of Public Health in maternal and child health?” That made a lot of sense, so I did, and that fall I took the required epidemiology course, and that was the first time I had ever heard the word epidemiology. And it was the first I had been introduced to the methodology and the rigor and the focus of it, and I said “Well that’s what I need to do, I need to go into epidemiology.” So I met with the Department Chair, Doctor Cassel, and I said I would like to transfer to epidemiology, and he said something that I think is true and I have said it over and over during my years. He said, “Epidemiologists aren’t made, they’re born.” And I know what he means by that: some people think individual to individual, and some people think population to population. So I said, “OK, well I’m willing to take the risk,” and he was too.
MM: What person would you single out as having most strongly influenced your career?
CH: It was definitely John Cassel. His lectures in the graduate program at Chapel Hill were the core for all the epidemiology subdisciplines. I was blown away by his thinking and his process of working through things. It just made so much sense to me.
MM: What have you found to be the most important ingredient of a good collaboration?
CH: I think that you cannot do epidemiology by yourself, it’s just impossible, and most of the people I collaborate with are not epidemiologists, they are experts in some other field. And one thing I think we do is borrow well, and to borrow you have to also give, and so having a give and take relationship that’s based on respect for each other’s discipline, and humor, and learning each other’s language: I think all of those things are important, and I think my best collaborations had been when all those things have been in existence.
MM: Which has been your most influential article?
CH: It’s one that I coauthored with Ward Cates and Christopher Tietze, and it outlined what you need to do to study pregnancies after abortion in a rigorous way.1 And I think that it still stands as what one should do—from a study design perspective—to do that properly. I see it as influential because it led me to have the opportunity to speak before Congress when Surgeon General Koop had his report on the effects of abortion on women, and I was asked to participate in this hearing in the spring of 1989 to explain, and to have Doctor Koop explain, why he was not publishing the report on the effects of abortion on women. The article I had written, and the work that I had done, influenced Dr. Koop to say he agreed with me with respect to the lack of effect of induced abortion on subsequent pregnancies. I guess a close second to that article, or maybe more influential in the broader picture, is the article that we published in 1992 on low birth weight, very low birth weight, and infant mortality between African American college graduates married to African American college graduates, and comparing that to white college graduate couples.2 That really triggered a whole series of research around the impact of racism and stress-associated racism on reproductive health.
MM: Coming back to the abortion sequelae, it sounds like you are now addressing that again using new methods.
CH: Yes, the old methods and the new methods. We just published a report in the National Academy of Sciences, Engineering, and Medicine on the quality and availability of abortion services in the United States. And there was a chapter on the kinds of ill effects that people attribute to abortion, including psychological. And since 1989 there have been some excellent studies of the psychological impact, so we were able to say very definitive things about that, as well as the lack of association with breast cancer and the lack of association of abortion with pregnancy complications and outcomes.
MM: What do you see as the role of epidemiologic organizations in the field?
CH: The Society for Epidemiologic Research really has brought out the teachings of the methods and encourages method development, and it is the one society where people who come from lots of different subdisciplines can come together and talk about the methods. I was very honored to be the President in 1988, which for me was kind of a big year because that was also the year we adopted our baby, and the meeting was in Vancouver. And we had just brought her home from Chile 2 weeks before the annual meeting, and so at my presidential address I lifted her up and I said “Welcome to the world of epidemiology!” And then later on, I also headed up the American College of Epidemiology, which I think is important because it supports the profession of epidemiology, and it can really advocate for epidemiology, which I think is rather important nowadays because now it’s hard sometimes for institutions like the National Institutes of Health to understand the importance of the thinking of epidemiology. Because we have gotten to be so good with methods, sometimes we get to be equated with biostatistics, and then why do you need both? We do need both, and the college really I think does a good job of distinguishing, and so I was happy to lead both of those organizations.
MM: How have you chosen your research questions?
CH: My dissertation director talked about the health theme in family planning, and how important it was to have healthy babies in order for people not to have so many babies. So a lot of my work was around that. But then as politics reared its head, I think that it’s also important to have the family planning theme in health, so a lot of my research in more recent years has been trying to introduce aspects of that, which is a little different. It says to have health, you also need to have family planning, and it’s not just for healthy babies. One of the pieces of that has been in understanding that not everyone has equal access to family planning, and why that is true, and how to eliminate the discrimination in both family planning and reproductive health in general.
MM: What has been epidemiology’s most important contribution to society?
CH: Epidemiology speaks truth to power. And I think that if you go back to where we see our origins in infectious disease, and the famous taking the pump handle off to deal with cholera before the microscope saw it—we break assumptions with data, and to the extent that we are allowed to do that, I think we make quite a contribution. It’s difficult sometimes see that because we don’t always get the credit for moving forward, but I really do believe—especially today where we see a disconnect between what we know needs to be done and what is being done—that when we fill in that gap and continue to present the data, that it’s maybe like water drops on rock; it will have an impact.
MM: What is your assessment of the current state of epidemiology?
CH: Recently we have really been bombarded with really fake news, and I think it’s up to the health of epidemiology to face facts, and to keep pushing facts. In the past, I would say that we were spending a lot of time beating up on each other: “You haven’t done this quite right and it’s going to make this much difference in your results.” Battles like that tended to obscure the big picture. So if epidemiology is going to have the impact that I think it can, we need to be more aware of that and to do the best job we can explaining that observational science is going to have some differences, and that we need to recognize those, but not focus on them. To the extent that we can do that, and to distinguish the thinking of epidemiology from the methods of epidemiology, I think we have a strong future.
ABOUT THE AUTHOR
TIMOTHY L. LASH is Rollins Professor and Chair of the Department of Epidemiology at the Rollins School of Public Health, Emory University and Editor-in-Chief of Epidemiology.