Maternal And Infant Health

Definitions of Reported Measures

  • Preterm birth is a singleton birth prior to 37 weeks of gestation (about 8.5 months). 
  • Very preterm birth is a singleton birth prior to 32 weeks of gestation.
  • Term low birthweight birth is a singleton birth born at full term (37 weeks of gestation) and with a birthweight less than 2,500 grams.
  • Very low birthweight birth is a singleton birth born with a birthweight of less than 1,500 grams.
  • Infant mortality is a death of an infant less than one year of age. 
  • Neonatal mortality is a death of an infant less than 28 days of age. 
  • Postneonatal mortality is a death of an infant between 28 days and 12 months of age.
  • Perinatal mortality includes both stillbirths after 28 completed weeks of pregnancy and live births prior to 7 days of age. 
  • Total fertility rate (TFR) is a measure of the speed at which a population is reproducing. A TFR of 2000 suggests that the population is neither increasing nor decreasing, not considering the rates of in- and out-migration.
  • Sex ratio at birth is the number of males to females among term singleton births. Scientists generally expect this number to be close to 1.05.

How to Read Tables, Charts, and Maps

  • The 95% confidence interval (CI) is the range of values that likely contains the true rate in the population.
  • Conventional rates express the number of outcomes relative to the size of the population.  N/A indicates that the data are not available due to the number of events being less than 12.
  • Modeled rates are similar to conventional rates except that they further take into account the frequency of events in surrounding areas.  Modeled rates can be useful when there aren't enough events in an area to calculate rates in the conventional manner, and they are often useful for examining regional trends.
  • Total counts are listed next to conventional rates unless the total number of events is less than 12. They are typically not listed next to modeled rates.

Data Sources

  • Birth Statistical Master Files and Birth Cohort Files from the State of California, Department of Public Health, Office of Vital Statistics.  Denominators for total fertility rates are based on estimates from the California Department of Finance.
  • To maximize data quality, we exclude birth records for which the birthweight and length of pregnancy are nonsensical (for example, a four-kilogram newborn listed as being born three months preterm) using an established algorithm (See Alexander GR et al, Obstetrics and Gynecology 1996;87(2):163-8).

Limitations of the Data

  • It should be noted that the address reported by the mother is for the date of delivery, and may not reflect where the mother lived or worked during her pregnancy, or where the mother or infant live following delivery.

Suggested Citation

Tracking California, Public Health Institute. Maternal and Infant Health data. Accessed [Month/Day/Year] from

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