Maternal and Pregnancy Factors Associated with Cesarean Delivery among Term, Singleton, Cephalic Births without Previous Cesarean Delivery in the United States: A Population-based Analysis of 2023 National Vital Statistics System Natality Data

Abstract

Background: Caesarean delivery accounts for a substantial proportion of births in the United States, including term, singleton, cephalic births without a previous caesarean delivery. Identifying maternal, pregnancy, and labour characteristics associated with caesarean delivery may help to describe patterns of delivery care among women with otherwise uncomplicated pregnancies. Objective: To examine maternal, pregnancy, labour, and birth characteristics associated with caesarean delivery among term, singleton, cephalic births without a previous caesarean delivery in the United States. Methods: A cross-sectional study was conducted using data from the 2023 National Vital Statistics System Natality Public Use File. The analysis was restricted to term, singleton births with cephalic presentation and no previous caesarean delivery. Records with missing, unknown, or unstated values for variables included in the adjusted model were excluded. Maternal, pregnancy, labour, and birth characteristics were compared between vaginal and caesarean deliveries using chi-square tests and independent-samples t-tests. Multivariable logistic regression was used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs). Results: The final analytical sample comprised 2,178,731 term, singleton, cephalic births without a previous caesarean delivery, including 385,523 (17.7%) caesarean deliveries. In the adjusted model, women aged 40 years or older had higher odds of caesarean delivery than women younger than 20 years (aOR 5.36, 95% CI 5.21–5.51). Higher odds were also observed among women with obesity class III (aOR 3.52, 95% CI 3.47–3.58), pregestational diabetes (aOR 1.84, 95% CI 1.78–1.90), chronic hypertension (aOR 1.32, 95% CI 1.29–1.35), gestational hypertension (aOR 1.26, 95% CI 1.24–1.28), and labour anaesthesia (aOR 2.00, 95% CI 1.97–2.02). Foreign-born women had higher odds of caesarean delivery than US-born women (aOR 1.22, 95% CI 1.21–1.23). Multiparous women had lower odds of caesarean delivery than nulliparous women (aOR 0.22, 95% CI 0.22–0.22). Conclusion: Among term, singleton, cephalic births without a previous caesarean delivery recorded in the United States in 2023, caesarean delivery occurred more frequently among women who were older, had a higher pre-pregnancy BMI, experienced diabetes or hypertensive disorders during pregnancy, or gained more weight during pregnancy. Differences were also observed according to parity, nativity, and selected labour characteristics. These results indicate that variation in delivery mode persists even within a population considered to be at low risk. Information from national birth records can help to identify maternal and pregnancy characteristics associated with caesarean delivery and may support ongoing evaluations of obstetric care patterns. Further research using data with detailed clinical and hospital information may help to explain some of the observed differences across patient groups.