Definition: Percentage of infants born prior to 37 weeks of gestation, based on last menstrual period estimate of gestational age (e.g., in 2016, 8.7% of infants born to California women were born preterm).
Data Source: California Dept. of Public Health, Birth Statistical Master Files; CDC WONDER, Natality Public-Use Data (Feb. 2019).
Footnote: County-level data reflect the mother's county of residence, not the county in which the birth occurred. Data exclude infants for whom dates of mothers' last menses were not reported. The notation S refers to data that have been suppressed because there were fewer than 20 preterm births. N/A means that data are not available.