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Epidemiology

Over the last 50 years, the Division of Intramural Population Health Research (DIPHR) of the Eunice Kennedy Shriver National Institute of Child Health and Human Development has become a world-renowned center for population health research. Both this research focus and prestige of the journal, Epidemiology, make it the ideal venue for us to commemorate DIPHR’s special occasion. We have selected 13 peer-reviewed papers authored by current and past members of the Epidemiology Branch of DIPHR and outside partners who came to celebrate the milestone with DIPHR. The authors span from students to senior scientists. The papers are chosen to reflect the range of DIPHR’s impact, which has improved knowledge in population health issues related to pollution, lifestyle, behavioral and psychosocial factors, biologic and hormonal cycles, the interaction between nutrition and genetics, female and male fertility, maternal and children’s health, life-course health, low-cost interventions, and more. DIPHR remains committed to promoting the health and well-being of populations, both nationally and globally, through our research and mentorship. We envision that the collection of papers within this issue will enrich understanding of key issues that affect the populations we serve, as well as the research enterprise in which we engage. To begin this special issue, the paper by Dr. Grewal and her colleagues1 highlights the historical advances and achievements that DIPHR has made within child health and human development over the last 50 years, current research topics, and the future direction of the Division. Next, Drs. Cheng and Mistry2 provide a thoughtful commentary that is highly germane to the missions of DIPHR and NICHD, describing the unique significance of children’s health in addressing disparities across the life course through their discussion of the “5 Ds.” Their work recognizes the need for appreciating the developmental origins of health and the role of social factors in contributing to inequities in healthcare. The paper by Holland and colleagues3 then trains attention on the importance of training in the progress of our fields, through the lens of the paths taken by current and future DIHPR postdoctoral fellows. Their analysis explores how the length of a postdoctoral fellowship and the specific research discipline can affect future research performance metrics—information that can help fellows in making professional decisions.3 In conjunction with the anniversary commemoration, DIPHR also organized a Student Paper Prize competition. One of the two students recognized with this prize, Dr. Kahn et al,4 authored an excellent paper assessing the associations between adiposity and sperm concentration, motility, and morphology. Her findings revealed that men who were overweight or obese in their twenties were much more likely to meet criteria for subfertility than normal-weight men, emphasizing the influence of the health status of both partners on reproductive outcomes.4 The following two papers featured methodological innovations in epidemiology. First, Dr. Perkins and colleagues5 found that a principled recalibration of biomarker assays can reduce measurement error and improve inference, a conclusion that can aid future studies in gauging the accuracy of findings. Second, Drs. Westreich and Mooney6 investigate ways of calculating a more precise number of individuals needed to treat, identifying major considerations in arriving at correct interpretations of both observational and interventional research. An additional series of papers examine specific substantive research topics. One collaborative paper is led by a former DIPHR postdoctoral fellow, Dr. Schliep et al.7 This paper reported that higher perceived stress was associated with a marginally higher risk of anovulation and longer time to pregnancy in women attempting natural conception after a history of pregnancy loss. These results further our understanding of the mechanisms that may adversely affect a woman’s ability to become pregnant.7 Another collaborative paper led by a current DIPHR fellow, Dr. Kim et al8 highlight the relationship between certain preconception fatty acids, substrates for prostaglandin and steroid hormone synthesis, and the probability of pregnancy loss and live birth, offering crucial insight about preconception health and diet for couples of reproductive age. Dr. Lin and colleagues9 leverage the NICHD Fetal Growth Studies to show that shorter telomere length in early pregnancy was associated with greater risk of subsequent gestational diabetes diagnosis in women younger than age 30, but not older women. Drs. Nianogo and Arah10 reveal that childhood obesity remains a risk factor for adult type-2 diabetes mellitus independent of adult obesity—a vital illustration of the developmental origins of obesity and the potential life-long effects of a child’s health. Dr. Huang and colleagues11 show a transgenerational association between higher maternal education and lower risk of metabolic syndrome in offspring. Another former postdoctoral fellow, Dr. Bell et al12 led a collaborative paper that finds a relationship between prenatal exposure to persistent organic pollutants and an increased risk of large-for-gestational-age babies. The final paper in this special issue was led by Dr. Buck Louis et al,13 who served as DIPHR’s Division Director for eight years. Their paper characterizes the novel research paradigm of the exposome. In particular, they quantify patterns of endocrine disrupting chemicals (EDCs) and other environmental exposures during pregnancy and establish that concentrations of EDCs are not stable across pregnancy.13 In sum, we are proud that the first 50 years of research conducted by DIPHR scientists with outside partners has been valuable in promoting current understanding of population health across the lifespan. Looking forward, we aim for the Division to sustain a prominent role in the field, with many more years of increasing productivity and scientific achievement.

50 Years in Less Than 1000 Words