Sociodemographic and Obstetric Characteristics
Research staff blinded to condition collected sociodemographic and obstetric characteristics. Birth date, socioeconomic status, cohabitation with partner, marital status, educational attainment, race (categories: American Indian/Alaska Native, Asian, Black or African American, European, Middle Eastern, Native Hawaiian or Other Pacific Islander, North African, White, or more than 1 race), and ethnicity (Chicana, Hispanic, Latine, or Mexican) were collected via interview. Income to needs ratio was calculated by dividing the total reported household income for the past year by the poverty threshold for that year corresponding to the number of persons living in the household, specified by the US Census Bureau. Two research staff performed medical record reviews, which were assigned by an independent staff member with 50% overlap in records reviewed to ensure consistency across the 2 reviewers. GA was calculated from medical record review using early ultrasonography measures and/or date of last menstrual period applying the American College of Obstetricians and Gynecologists guidelines.