Collaborative ECHO research led by Rachel Kelly, PhD and Nicole Prince, PhD, of Brigham and Women’s Hospital and Harvard Medical School, and Donghai Liang, PhD, MPH of Emory University analyzes the relationship between small molecules in a mother’s blood during pregnancy and childhood BMI. This research, titled “Metabolomic Data Presents Challenges for Epidemiological Meta-Analysis: A Case Study of Childhood Body Mass Index from the ECHO Consortium,” is published in Metabolomics.
A child’s body mass index (BMI) can affect their future health. Some researchers are exploring the connection between factors during pregnancy and childhood BMI. Increasingly, researchers use molecular data to analyze the relationship between pregnancy and childhood health outcomes, sometimes combining molecular data from multiple study sites to increase the statistical power of these analyses.
In this study, ECHO researchers combined the results from multiple ECHO Cohort Study Sites to determine whether a relationship existed between small molecules in the mother’s blood during pregnancy and their child’s later BMI. It also aimed to use these data to test a framework for analyzing molecular data across multiple studies.
The study involved mothers in the second and third trimesters of pregnancy and their children from multiple study sites: the Atlanta ECHO Cohort, the New Hampshire Birth Cohort, and the Vitamin D Antenatal Asthma Reduction Trial. Pregnant participants from these sites provided blood samples, which were then used to measure a range of small molecules that provide information on each participant’s health and environment and the biological or genetic factors that could affect their pregnancy. These participants and their children were observed and assessed across pregnancy and the child’s early life. In this analysis, the authors used data from the aforementioned three study sites to evaluate the relationship between molecules measured during pregnancy and BMI at age 2, aiming to identify relationships that were consistent across all three.
The research team found that of all the small molecules tested, 20 showed up in all study sites, and 127 showed up in at least two. The study found that the levels of only six small molecules, primarily related to maternal diet, were associated with child BMI across all sites. However, statistical analysis across these study sites did not identify significant associations between these molecules and child BMI.
This study demonstrates some of the challenges of harmonizing molecular data across diverse study sites and highlights important considerations for researchers trying to conduct similar analyses.
“Differences in how molecular data were collected and measured between the sites in this study made it difficult to draw strong conclusions on the relationship between small molecules during pregnancy and childhood BMI,” Dr. Kelly said. “Future analyses could involve larger, more standardized studies that all use the same methods for sample collection and measurement of molecules present, which would improve the reliability and reproducibility of results.”
Many ECHO Cohort Study Sites are now measuring small molecules in mothers and children with a standardized approach under the ECHO Cohort Data Collection Protocol. ECHO researchers have an opportunity to use these data to power analyses that can explore the relationship between pregnancy health and child health outcomes.