Ben Courchia MD

Okay, we're joined for this next section by two authors from this very special series. We have the pleasure of having on today Dr. Tim Nelin and Dr. Yarden Freeman. Welcome to the podcast. We're very excited to have you here to discuss health equity and the life course health development for preterm infants. I want to dive into a few of the topics because we have a limited amount of time, and I feel like we needed three times that amount of time to discuss the dense papers that you've both written.

Tim, I wanted to start with you talking a little bit about neighborhood environments and preterm health development. I think in the paper that you wrote, you talk about this concept of micro and macro effects. I think it's an interesting concept in terms of looking at that and how that affects the health outcome of preterm infants. Can you give us a bit of an overview of how these neighborhood environments play a role in that epidemiology?

Tim Nelin

Yeah, that is a wonderful question. Thank you so much for starting there. And this may be a little bit of an oversimplification, but I'd like to break it down into thinking about the macroenvironment and the microenvironment. The microenvironmental exposures are specific to the individual's non-genetic exposures that may include things like diet, physical activity, smoking, social relationships. The macroenvironment contains different exposures that an individual has a little bit less control over – things like ambient air pollution exposure, neighborhood violence, green space, or neighborhood social vulnerability. We think that both of those are really connected to perinatal health outcomes. When we look broadly at different markers of macroenvironmental exposures, we find that the same exposures associated with preterm birth risk are often associated with adverse health outcomes of preterm infants. That’s important because some of the same exposures that contributed to an infant’s preterm birth risk are the same exposures that infant will face once they leave the hospital.

Ben Courchia MD

Yeah. And one of the examples you mentioned is bronchopulmonary dysplasia and how there are stark differences in incidences and prevalence of that specific morbidity depending on various factors. Can you tell us a little bit more about that, or are there other morbidities that are quite striking in how they differ between different environments?

Tim Nelin

Yeah. I think we would be remiss not to mention the racial disparities here. Black birthing parents are twice as likely to give birth preterm compared to white birthing parents. When we look at births at less than 28 weeks, black infants are more than three times more likely to be born at that gestation. These are the infants most vulnerable and most at risk for BPD, neurodevelopmental impairment, longer hospital stays, and adverse outcomes after NICU discharge. My group, with Heather Burris, looked at markers of the neighborhood environment quantified by the CDC Social Vulnerability Index and found that higher neighborhood social vulnerability was associated with higher odds of ED visits and inpatient readmissions in the year after NICU discharge among infants with BPD.

Ben Courchia MD

Thank you very much. Yarden, I wanted to segue into your article, titled “A Narrative Review of the Association Between Prematurity and Attention Deficit Hyperactivity Disorder and Accompanying Inequities Across the Life Course.” I think you do a tremendous job illustrating some of the points we’ve already started discussing, focusing specifically on ADHD. Can you tell us a little bit about how the inequities in preterm birth and the associated morbidities like ADHD translate into health disparities that last throughout the lives of these children?

Yarden S. Fraiman

Yeah, absolutely. Thanks so much for that question. Many of us know about the increased risk of developing ADHD among preterm infants, particularly those born at lower gestational ages. There’s even data to support that late preterm infants also have an increased risk. As Tim mentioned, we already know the inequities that exist in preterm birth, particularly among black birthing parents and their infants. We’ve done a really good job studying that inequity in neonatology, and then our pediatric colleagues examine inequities in childhood. But we haven’t fully connected how inequity in one period of life relates to inequity later on.

When we think about ADHD, we know from pediatric literature that there are inequities in symptom recognition, referral, evaluation, diagnosis, treatment, and maintenance. We call that the ADHD care cascade. So instead of studying inequity at one point in time, we can start to see how inequities are connected. Black birthing parents are more likely to have preterm infants, putting those babies at higher risk for ADHD. After NICU discharge, minoritized infants are less likely to be seen in early intervention or high-risk follow-up programs that perform neurodevelopmental screening. When minoritized children get to school, they are more likely to be identified as having problematic behaviors but less likely to receive an ADHD diagnosis. That means they don’t get medication or the appropriate services, and the inequity grows over time.

ADHD is just one example—similar patterns exist for asthma and BPD. What we wanted to highlight is that it’s time we stop measuring inequity cross-sectionally and begin to measure it longitudinally, following inequity over time.

Ben Courchia MD

Yeah, two words I’m taking away from your paper are “cascade” and “layers.” You have a beautiful figure showing the variables involved in identifying, diagnosing, and managing ADHD. You also discuss how inequities can layer over time. ADHD is particularly interesting because it’s such a unique pathology. You write that there are unique characteristics of ADHD among preterm-born children, suggesting a unique subtype and pathophysiology in this population. You talk about the ADHD being divided into three subtypes: the hyperactive or impulsive, the inattentive, or combined hyperactive and inattentive. While the combined phenotype is the most common in the general population, among preterm-born children the inattentive subtype is most common. This can lead to increased misdiagnoses since it’s the less frequent subtype overall.

You also discuss whether the increased risk of ADHD among preterm infants might result from systemic bias due to increased medical monitoring and screening. But you conclude that it’s unlikely that increased monitoring explains the excess ADHD diagnoses among preterm-born children. It’s a fascinating lens into the life of our preemies as they leave the NICU.

Tim, I wanted to ask about the educational and economic consequences. What are some of the social and educational impacts of these early health disparities as babies grow into adolescence and adulthood?

Tim Nelin