Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2024 Sep 3;7(9):e2435887.
doi: 10.1001/jamanetworkopen.2024.35887.

Risk and Protective Factors for Preterm Birth Among Racial, Ethnic, and Socioeconomic Groups in California

Laura L Jelliffe-Pawlowski  1   2   3   4   5   6 , Rebecca J Baer  3   4   5   7   8 , Scott Oltman  1   2   3   4 , Safyer McKenzie-Sampson  3   4   9 , Patience Afulani  1   2   3   4 , Ribka Amsalu  3   4   7 , April J Bell  3   4   10 , Bridgette Blebu  4   11 , Kacie C A Blackman  4   12 , Christina D Chambers  4   5   8 , Jean Costello  3   4   13 , Jonathan Fuchs  3   4   13 , Odessa Garay  4   14 , Kayla L Karvonen  3   15 , Miriam Kuppermann  3   4   7 , Audrey Lyndon  4   16 , Charles E McCulloch  1   4 , Giannina Ong  3   7 , Carolyn Ponting  4   17 , Larry Rand  3   4   7 , Elizabeth E Rogers  4   12 , Kelli K Ryckman  4   18 , Solaire Spellen  3   4   7 , Akila Subramaniam  4   19 , Louie Swander  12 , Kelly D Taylor  2   3   4   20 , Schyneida Williams  15   21 , Karen M Tabb  4   22
Affiliations

Risk and Protective Factors for Preterm Birth Among Racial, Ethnic, and Socioeconomic Groups in California

Laura L Jelliffe-Pawlowski et al. JAMA Netw Open. .

Abstract

Importance: Preterm birth (PTB) (gestational age <37 weeks) is a major cause of infant mortality and morbidity in the US and is marked by racial and ethnic and socioeconomic inequities. Further research is needed to elucidate the association of risk and protective factors with trends in PTB rates and with related inequities.

Objective: To describe the association of PTB rates with inequities as well as related risk and protective factors over the past decade in a US population-based cohort.

Design, setting, and participants: This retrospective cohort study of singleton live births in California from January 1, 2011, to December 31, 2022, was conducted using vital statistics records and hospital records. The cohort included births with a gestational age of 22 to 44 weeks.

Main outcomes and measures: Preterm birth rates by racial and ethnic group and by public and nonpublic insurance (considered as a proxy for socioeconomic status) were studied across years. Log-linear regression (relative risks with 95% CIs) was used to evaluate risk and protective factors within groups. Associations of PTB rates with risk and protective factors were assessed.

Results: This study included 5 431 018 singleton live births to individuals who identified as American Indian or Alaska Native (0.3%), Asian (14.2%), Black (4.9%), Hispanic (47.8%), or White (27.0%). A total of 43.1% of births were to individuals with public health insurance. From 2011 to 2022, the overall PTB rate increased from 6.8% to 7.5% (change [SE], 10.6% [0.6%]; z score of 18.5; P < .001). Differences in PTB rates and associated changes were observed for racial and ethnic groups and insurance groups. For example, 2022 PTB rates ranged from 5.8% among White individuals with nonpublic insurance to 11.3% among Black individuals with public health insurance. From 2011 to 2022, PTB rates decreased from 9.1% to 8.8% (change [SE], -3.5% [4.2]; z score of -0.8; P = .42) among Black individuals with nonpublic insurance, whereas they increased from 6.4% to 9.5% (change [SE], 49.8% [16.0%]; z score of 3.1; P = .002) among American Indian or Alaska Native individuals with nonpublic insurance. Increases in some risk factors (eg, preexisting diabetes, sexually transmitted infections, mental health conditions) were observed in most groups, and decreases in some protective factors (eg, participation in the California Women, Infants, and Children program) (P for trend < .001 from 2011 to 2021) were observed mostly in low-income groups.

Conclusions and relevance: In this cohort study of singleton live births in California, PTB rates increased in many groups. Persistent racial and ethnic and socioeconomic inequities were also observed. Changes in risk and protective factors provided clues to patterns of PTB. These data point to an urgent need to address factors associated with PTB at both the individual and population levels.

PubMed Disclaimer

Conflict of interest statement

Conflict of Interest Disclosures: Dr Jelliffe-Pawlowski reported receiving grants from the University of California, San Francisco during the conduct of the study; receiving grants from the National Institutes of Health outside the submitted work; having a patent pending for tools predicting preterm birth; having a patent pending for a newborn metabolic vulnerability model for identifying preterm infants at risk of adverse outcomes; and founding and serving as chief executive officer of EGG Healthy Pregnancy, a technology company focused on creating digital therapeutics to address preterm birth and related adverse pregnancy outcomes. Mr Oltman reported having a patent pending for a newborn metabolic vulnerability model for identifying preterm infants at risk of adverse outcomes. Dr Rogers reported reported receiving grants from the University of California, San Francisco during the conduct of the study and receiving grants from the National Institutes of Health outside the submitted work. Dr Ryckman reported receiving grants from the University of California, San Francisco during the conduct of the study; receiving grants from the National Institutes of Health outside the submitted work; having a patent pending for tools predicting preterm birth; and having a patent pending for a newborn metabolic vulnerability model for identifying preterm infants at risk of adverse outcomes. No other disclosures were reported.

Figures

Figure 1.
Figure 1.. Preterm Birth (PTB) Rates Among California Singletons With Public Insurance by Racial and Ethnic Groups, 2011 to 2022
Gestational age of less than 37 completed weeks was considered preterm. P values were determined with the Armitage-Cochrane test for trend (2-tailed).
Figure 2.
Figure 2.. Preterm Birth (PTB) Rates Among California Singletons With Nonpublic Insurance by Racial and Ethnic Groups, 2011 to 2022
Gestational age of less than 37 completed weeks at birth was considered preterm. P values were determined with the Armitage-Cochrane test for trend (2-tailed).
Figure 3.
Figure 3.. Risk and Protective Factors for Preterm Birth (PTB) by Insurance and Racial and Ethnic Groups
Gestational age of less than 37 completed weeks was considered preterm. All comparisons were yes vs no except for age (18-34 years [referent]), education (12 years), FIPS county code of residence (1 [most urban]), BMI (18.5-29.9), and IPI (18-59 months). More complete coding for risk and protective factors is presented in eTable 1 in Supplement 1. AI/AN indicates American Indian or Alaska Native; BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); FIPS, Federal Information Processing Standard (1 [most urban] to 6 [most rural]); IPI, interpregnancy interval; NC, not calculated (when n < 11 per state requirements [to protect individual-level privacy]); NH/OPI, Native Hawaiian or Other Pacific Islander; NS, nonsignificant; STI, sexually transmitted infection; WIC, California Women, Infants, and Children program.
See this image and copyright information in PMC

Comment in

Similar articles

See all similar articles

Cited by

References

    1. Ohuma EO, Moller AB, Bradley E, et al. . National, regional, and global estimates of preterm birth in 2020, with trends from 2010: a systematic analysis. Lancet. 2023;402(10409):1261-1271. doi:10.1016/S0140-6736(23)00878-4 - DOI - PubMed
    1. Percentage of births born preterm by state. Centers for Disease Control and Prevention National Center for Health Statistics . Accessed May 22, 2024. https://www.cdc.gov/nchs/pressroom/sosmap/preterm_births/preterm.htm
    1. Martin JA, Osterman MJK. Shifts in the distribution of births by gestational age: United States, 2014-2022. Natl Vital Stat Rep. 2024;73(1):1-11. - PubMed
    1. Martin JA, Hamilton BE, Osterman MJK. Births in the United States, 2022. NCHS Data Brief. 2023;(477):1-8. - PubMed
    1. Phelps AJD, Holmgren C. Relationship between risk factor profile and prescription of low-dose aspirin for preeclampsia prevention. Arch Gynecol Obstet. 2023;308(4):1279-1286. doi:10.1007/s00404-022-06773-0 - DOI - PubMed

Publication types