Risk Factors and Maternal-Fetal Outcomes of Pregnancies Complicated by Pre-Eclampsia

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Risk Factors and Maternal-Fetal Outcomes of Pregnancies Complicated by Pre-Eclampsia, Following Cesarean Section After a Trial Vaginal Birth

Introduction

Pre-eclampsia, a hypertensive disorder unique to pregnancy, remains a leading cause of maternal and neonatal morbidity and mortality worldwide. Characterized by new-onset hypertension and end-organ dysfunction after 20 weeks of gestation, severe pre-eclampsia necessitates timely intervention to prevent life-threatening complications such as eclampsia, HELLP syndrome (hemolysis, elevated liver enzymes, low platelets), and placental abruption. While delivery is the definitive treatment, the optimal mode of delivery—vaginal birth versus cesarean section—remains a subject of clinical debate. Current guidelines emphasize that pre-eclampsia alone does not mandate cesarean delivery unless complications arise. However, in practice, many patients and clinicians opt for direct cesarean section due to concerns about maternal or fetal deterioration during labor. This study investigates the outcomes and risk factors associated with transfer-cesarean sections (those performed after initiating vaginal labor) in severe pre-eclampsia cases, providing critical insights into the safety and feasibility of vaginal trials in this high-risk population.

Study Design and Methodology

This retrospective cohort study, conducted at Fujian Maternity and Child Health Hospital in China, analyzed data from 1,626 pregnancies complicated by severe pre-eclampsia between January 2015 and July 2019. Severe pre-eclampsia was defined using criteria from the National High Blood Pressure Education Program Working Group (2000), including systolic blood pressure ≥160 mmHg, diastolic blood pressure ≥110 mmHg, proteinuria ≥2.0 g/24 hours, or evidence of end-organ dysfunction. Exclusion criteria included multiple pregnancies, fetal demise, or pre-existing medical conditions.

Participants were stratified into three groups:

  1. Direct cesarean section: Planned operative delivery without labor (n=1,073).
  2. Vaginal delivery: Successful vaginal birth after induced or spontaneous labor (n=337).
  3. Transfer-cesarean section: Cesarean performed after initiating vaginal labor (n=216).

Demographic variables, maternal outcomes (e.g., postpartum hemorrhage, hypertensive crises), and neonatal outcomes (e.g., Apgar scores, NICU admission) were compared across groups. Statistical analyses included χ² tests, ANOVA, Kruskal-Wallis tests, and multivariable logistic regression to identify risk factors for transfer-cesarean sections.

Key Findings

Maternal Outcomes

The study revealed significant disparities in maternal complications among the groups. Direct cesarean sections were associated with higher rates of postpartum hemorrhage (7.7% vs. 4.5% in vaginal deliveries) and blood transfusions (2.4% vs. 0.6%). Patients undergoing direct cesarean sections also faced prolonged hospitalization (>7 days in 10.4% of cases vs. 0.6% for vaginal deliveries). Conversely, maternal outcomes in the transfer-cesarean group mirrored those of direct cesarean sections, with no statistically significant differences in hemorrhage rates (7.2%), transfusion needs (1.9%), or hospitalization duration (12.0%).

Notably, severe complications like eclampsia (0.1% in direct cesarean) and HELLP syndrome (0.6% in direct cesarean) were rare across all groups. However, placental abruption occurred in 2.9% of direct cesarean cases, compared to 2.1% in vaginal deliveries and 3.6% in transfer-cesarean cases.

Neonatal Outcomes

Neonates born via direct cesarean sections exhibited higher rates of adverse outcomes compared to vaginal deliveries. Apgar scores <7 at 5 minutes were observed in 7.5% of direct cesarean births versus 2.7% in vaginal deliveries. NICU admission rates were also elevated in the direct cesarean group (26.0% vs. 18.4% for vaginal deliveries). Transfer-cesarean sections showed intermediate neonatal outcomes, with 5.1% of neonates scoring <7 on 5-minute Apgar tests and 21.8% requiring NICU care.

In term pregnancies (≥37 weeks), neonates delivered by transfer-cesarean sections had higher rates of low 1-minute Apgar scores (12.8%) and NICU admissions (21.8%) compared to vaginal deliveries (11.6% and 18.4%, respectively), though birth weights and gestational ages were comparable across groups.

Risk Factors for Transfer-Cesarean Section

Multivariable logistic regression identified two independent risk factors for failed vaginal trials:

  1. Cephalopelvic disproportion: Odds ratio (OR) 2.13 (95% CI: 1.43–8.13).
  2. Fetal distress: OR 2.42 (95% CI: 1.76–6.65).

These factors accounted for 59% and 32% of transfer-cesarean indications, respectively. Other variables, such as maternal age, parity, and blood pressure at admission, did not significantly predict conversion to cesarean.

Clinical Implications

The findings challenge the prevalent preference for direct cesarean sections in severe pre-eclampsia. Although direct cesarean avoided intrapartum complications, it was linked to higher maternal morbidity (e.g., hemorrhage, prolonged recovery) and poorer neonatal outcomes compared to vaginal deliveries. Critically, transfer-cesarean sections did not exacerbate risks beyond those of direct cesarean deliveries, underscoring the safety of attempting vaginal labor in eligible patients.

The study highlights the importance of prenatal assessments to identify cephalopelvic disproportion and continuous fetal monitoring during labor to detect distress early. These measures could reduce unnecessary cesarean sections while ensuring timely intervention when needed. Additionally, the data support current guidelines advocating vaginal delivery in severe pre-eclampsia when no contraindications exist.

Conclusion

For pregnancies complicated by severe pre-eclampsia, a trial of labor is a viable and safe option that does not increase maternal or neonatal risks compared to direct cesarean sections. The key to optimizing outcomes lies in meticulous patient selection, vigilant intrapartum monitoring, and prompt intervention for cephalopelvic disproportion or fetal distress. These strategies align with global efforts to reduce cesarean section rates without compromising safety, offering a balanced approach to managing one of pregnancy’s most challenging complications.

http://doi.org/10.1097/CM9.0000000000001452

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