Overview

The investigators are committed to identifying the optimal timing of delivery for low-risk pregnancies. While current guidelines typically recommend induction at 41 weeks, emerging evidence suggests that elective induction at 39 weeks may lead to improved maternal and neonatal outcomes. The U.S.-based ARRIVE trial demonstrated that induction at 39 weeks significantly reduced cesarean delivery rates compared to expectant management, and a similar randomized controlled trial (French-ARRIVE) is ongoing in France. However, population-specific evidence for the Chinese population remains lacking.

This study is designed to establish a prospective cohort of low-risk pregnant women in China, comparing the effects of induction at 39 weeks, induction at 41 weeks, and expectant management on cesarean section rates and other maternal and neonatal outcomes. In addition, multi-omics technologies will be employed to analyze cord blood samples-including metabolomics and proteomics-to identify early biomarkers potentially associated with long-term child health. The study will begin with a pilot phase to assess feasibility and inform operational strategies for large-scale implementation.

The ultimate goal of this project is to generate evidence tailored to the Chinese population to support more individualized decision-making, improve clinical outcomes, and enhance maternal and neonatal safety.

Eligibility

Inclusion Criteria:

1. Age ≥18 years.
2. Singleton pregnancy or twin pregnancy reduced to singleton before 14 weeks.
3. Gestational age of 38 weeks 6 days or 39 weeks 0 days at randomization.
4. Eligible for vaginal delivery with a desire for vaginal birth.
5. Reliable gestational age determination.
6. Maternal and fetal conditions assessed as favorable by at least two senior obstetricians, with no indications requiring delivery before 41 weeks.
7. Ability to understand study information and provide informed consent.

Exclusion Criteria:

1. First ultrasound estimate >13 weeks 6 days.
2. Planned induction before 41 weeks.
3. Planned cesarean delivery or contraindications to vaginal delivery.
4. Already delivered, in labor, or ruptured membranes at enrollment.
5. Placenta previa, vasa previa, placenta accreta, or placental abruption.
6. Contraindications to induction (e.g., cervical cancer, history of uterine rupture, genital tract malformations, abnormal fetal position, cord prolapse).
7. Active vaginal bleeding exceeding spotting.
8. History of cesarean delivery or uterine/cervical surgery.
9. Cervical cerclage during this pregnancy.
10. Maternal conditions not suitable for expectant management beyond 39 weeks (e.g., pregestational diabetes, gestational diabetes requiring insulin, hypertensive disorders, intrahepatic cholestasis of pregnancy).
11. Fetal conditions not suitable for expectant management beyond 39 weeks (e.g., fetal death, major anomalies, growth restriction, macrosomia, anemia, oligohydramnios, polyhydramnios).
12. Maternal infections or positive screenings for sexually transmitted pathogens or group B Streptococcus.
13. Planned delivery at a non-study facility.
14. Participation in another intervention study affecting delivery management.