ABSTRACT The Asian population in the U.S. has nearly doubled since the year 2000. Overall, 6.5% of births in the U.S. are to Asian people, yet a recently published ECHO Cohort analysis of pregnancies indicated that only 5.0% of the nearly 22,000 pregnancies included were to Asian people, representing just over 1,000 pregnant Asians. Despite efforts to be inclusive at enrollment across individual cohorts, the ECHO Cohort may include too few pregnant people of this underrepresented minority group to allow for meaningful examination of important race-related associations. Concerns about insufficient statistical power are heightened when analyses require disaggregation of data by Asian ethnicity due to heterogeneous risks. This proposal aims to increase the power and significance of the ECHO Cohort by enrolling an additional 780 pregnant Asian people representing multiple Asian ethnic groups from the three largest healthcare systems in the Minneapolis/St. Paul metropolitan area, along with their conceiving partners and the index infant. Our institutional expertise supports our focus on physical & chemical and lifestyle measures for our Specialized Exposures, and obesity as our Specialized Outcome. This study will allow us to further examine environmental health disparities among Asians, particularly among Southeast Asians such at the Hmong, who overwhelmingly represent the largest Asian ethnicity in Minnesota. For example, reproductive-aged Hmong women have been found to have significantly higher levels of certain phthalate metabolites compared to NHANES averages; given the documented effects of phthalates on fetal development, this is particularly concerning because Hmong women are roughly twice as likely to have had a birth in the last year compared to all other women. Our scientific aims will investigate the role of phthalates on sexually dimorphic outcomes including body composition in Asian ECHO Cohort participants. Our operational aim will use the exceptional performance of our research team during the first seven years of the ECHO Cohort to enroll multi- ethnic Asian participants. We will employ a novel recruitment methodology that transcends healthcare systems and that will identify a pregnant person at their first prenatal visit, then allowing research professionals from their own healthcare institution to recruit for our cohort. Upon enrollment, our study team will coordinate effortless biospecimen collection from their routine prenatal visits (and during delivery), while providing in-person (remote when necessary) study visits at our conveniently located Epidemiology Clinical Research Center; we will retain our Asian families using community-engaged approaches. Children resulting from the pregnancy, and the conceiving partner, will also be enrolled. 117 (15%) of these once-pregnant Asian people who may become pregnant again, along with their conceiving partners, will be re-enrolled into the ECHO Pre-Conception Pilot. This unprecedented col...