Maternal and neonatal characteristics associated with clinical outcomes of TOLAC from 2012–20 in the USA: Evidence from a retrospective cohort study

BACKGROUND: The risks of a few maternal and/or neonatal morbidities are higher with the trial of labour after caesarean (TOLAC) owing to unplanned caesarean delivery. Thus, it is imperative to consider the trade-off between the risk of side effects and the potential benefits before TOLAC utilisation and whether TOLAC should be provided to women with specific characteristics related to previous caesarean delivery. We aimed to investigate maternal and neonatal characteristics associated with TOLAC utilisation, compare maternal and/or neonatal morbidities in TOLAC women with women who chose planned caesarean deliveries, and assess specific characteristics related to maternal and/or neonatal morbidities in women with TOLAC utilisation. METHODS: In this retrospective cohort study, we used nationwide, linked birth and infant death data in the United States between 2012 and 2020, which covers all 50 states in the US. Poisson regression models using generalised estimating equations yielded adjusted prevalence ratios (aPRs) with 95% confidence intervals (CIs) of TOLAC utilisation and unsuccessful TOLAC by maternal and neonatal characteristics. Logistic regression models using generalised estimating equations yielded adjusted odds ratios (aORs) with 95% CIs of maternal and neonatal morbidities. Statistical analysis was performed from February 2022 to July 2022. FINDINGS: The sample included 4,898,441 women with mean (SD) maternal age years (5.4 years; range 13–50). Several specific maternal and neonatal characteristics were significantly associated with unsuccessful TOLAC, although women with TOLAC utilisation were associated with significantly lower risks of maternal unplanned hysterectomy (aOR, 0.60; 95% CI, 0.60–0.61), admission to intensive care (aOR, 0.84; 95% CI, 0.84–0.85), and neonatal seizures (aOR, 0.80; 95% CI, 0.74–0.84). In women who attempted TOLAC, advanced maternal age, higher maternal body mass index, more than 2 previous caesarean deliveries, having maternal co-morbidities and fetal malpresentation increased the likelihood of maternal and neonatal morbidities. INTERPRETATION: When utilising TOLAC, specific maternal and neonatal characteristics in pregnant women should be considered in conjunction with the potential benefits of TOLAC in preventing maternal and neonatal morbidities. FUNDING: This study is funded by the Clinical Medicine Plus X - Young Scholars Project, Peking University, the Fundamental Research Funds for the Central Universities (No: PKU2022LCXQ008).