Planned Primary Cesarean Delivery versus Attempted Labor in Low-Risk Pregnancies: Associations with Adverse Outcomes.

Objectives: To compare adverse outcomes among low-risk pregnancies with labor versus planned cesarean delivery (PL-CD).

Study design: A population-based, retrospective cohort study used U.S. vital statistic data from 2016-2021 in low-risk individuals delivered at 37 to 41 weeks with non-anomalous, singletons. Labor status was categorized as no labor (PL-CD) or labored. The primary outcome was a composite neonatal adverse outcome (CNAO); secondary outcomes were a composite maternal adverse outcome (CMAO) and infant death. Additional analysis was performed to re-categorize labor status into 3 groups: no labor (PL-CD), labored with vaginal delivery (VD) and labored with intrapartum cesarean (IN-CD). Multivariable Poisson regression models were utilized to estimate adjusted relative risk (aRR) and 95% confidence intervals (CI).

Results: Among 22,685,620 live births during the study period, 13,686,776 (60.3%) were included: 6.0% had PL-CD, and 94.0% labored. The rate of CNAO and CMAO were 7.97 and 3.17 per 1,000 live births, respectively. Compared to PL-CD, the risk of CNAO (aRR 0.58; 95% CI 0.57-0.59), infant death (aRR 0.59; 95% CI 0.57-0.62) and CMAO were lower (aRR 0.62; 95% CI 0.60-0.64) among those that labored overall. Compared to PL-CD by route of delivery, the risk of CNAO (aRR 0.47; 95% CI 0.46-0.48) and CAMO (aRR 0.45; 95% CI 0.44-0.47) was lower among VD, but higher (CANO, aRR 1.24; 95% 1.21-1.26, CAMO aRR 1.75; 95% CI 1.69-1.81) if delivered by IN-CD.

Conclusions: Among low-risk pregnancies, those who labored had a lower risk of composite adverse outcomes compared to those with planned cesarean, particularly if delivered vaginally.