Disparities in preterm birth: Impact of clinical, racial, and socioeconomic factors in <scp>US</scp> singleton pregnancies

BACKGROUND: The incidence of preterm births in the USA continues to rise, increasing the risk of adverse health outcomes for both neonates and pregnant persons. OBJECTIVES: This study identifies and quantifies risk factors associated with preterm birth in singleton pregnancies. METHODS: We analyzed de-identified data on singleton pregnancies from the National Institute of Child Health and Human Development Consortium on Safe Labor, encompassing clinical and demographic information from electronic medical records. RESULTS: Among 223 385 pregnancies, 11.7% resulted in preterm birth. Black/non-Hispanic individuals were over-represented among preterm births compared with term births (33.6% vs. 22.1%, P < 0.0001). In univariate analyses, preeclampsia/eclampsia (31.6% vs. 10.9%, P < 0.0001) and fetal anomalies (26.5% vs. 10.6%, P < 0.0001) were strongly associated with preterm birth. In multivariable models, short cervix (adjusted odds ratio [aOR] 4.1) and prior preterm birth (aOR 3.7) emerged as the strongest predictors. Additional independent risk factors included third-trimester bleeding (aOR 2.3), drug use (aOR 1.5), smoking (aOR 1.4), alcohol use (aOR 1.3), and antenatal urinary tract infection (aOR 1.3). Public insurance was independently associated with preterm birth (aOR 1.2). Notably, Black/non-Hispanic individuals were more likely to rely on public insurance (57.6%), underscoring the contribution of structural socioeconomic disparities to observed racial differences in preterm birth. CONCLUSIONS: Preterm birth is strongly associated with the pregnant individual's comorbidities, socioeconomic disadvantage, and obstetric complications. Targeted interventions to address health disparities, enhance prenatal care, and reduce modifiable risk factors are essential to improving perinatal outcomes.