ECHO MEND is a part of the ECHO program and investigates whether chemicals during a woman’s pregnancy affect the health of her developing child in the United States of America. The first phase of the study, known as the Global Alliance to Prevent Prematurity and Stillbirth (GAPPS), was founded in 2007 and recruited over 2,500 pregnant adult women to establish a large biorepository. Participants completed multiple surveys during prenatal and postnatal visits, medical records were abstracted, and biospecimen collection occurred over three visits during pregnancy and once at delivery. In 2017, the second phase, called the PATHWAYS-GAPPS study, recruited children born in the original GAPPS study. Over 650 mother-child dyads were assessed when aged 4 to 6 years at enrollment, and followed up when aged 8 to 9 years. In 2023, the third phase of the study commenced, known as the ECHO MEND study. The ECHO MEND study builds upon the PATHWAYS-GAPPS cohort, following participants from 6 to 12 years old. This third phase plans to follow participants annually over a seven-year period.