Moving Beyond Birthweight – Examining Developmental Origins of Disease Using Dynamic Postnatal Growth Indicators

Abstract

TPS 691: Methods of measurement, design and data analysis, Exhibition Hall, Ground floor, August 28, 2019, 3:00 PM - 4:30 PM Background: Barker first proposed that low birthweight may cause cardiovascular disease in adulthood. Since then, clinical epidemiologists developed additional child growth indicators, such as peak growth velocity (PGV), that help explain how growth patterns influence later-life health outcomes. Simultaneously, environmental epidemiologists examined chemical influences on birthweight, including assessment of critical windows and mixtures. However, little is known about how chemical exposure may impact growth velocities. Objective: We propose linking methodological advancements in environmental and clinical epidemiology to investigate the developmental origins of health and development. Methods: We demonstrate this approach using data from 422 mother-child pairs in the Swedish Environmental Longitudinal Mother and child Asthma and allergy (SELMA) study. First, we estimated timing of infant PGV using individual additive-logistic models with anthropometric measurements (body weight) from birth to 5.5 years. We then assessed PGV timing as an outcome variable in relation to prenatal PFOA exposure. The linear model was adjusted for sex, gestational age, mother’s age, weight, parity, smoking, fish consumption, and creatinine levels. Results: A doubling in prenatal PFOA levels was related to infant PGV occurring 25 days earlier among boys (p-value=0.02), but 38 days later among girls (p-value=0.01). Discussion: Compared to more complex growth modeling methods, the individual nonlinear growth curves were relatively easy to fit and allow characterization of dynamic growth indicators. In addition to PGV, and timing of PGV, velocities at clinically relevant age ranges may be estimated. These growth patterns can be flexibly modeled in relation to both upstream effects as demonstrated here with PFOA, and down-stream effects as classically demonstrated by Barker. Further, more complex methods for assessing mixtures or critical windows may be incorporated. This approach may help researchers further investigate how early life environmental exposures may impact child health and development, and the importance of childhood growth patterns according to Barker.