Sufentanil-ropivacaine combination is commonly used for epidural labor anesthesia, but is associated with some adverse events. Dexmedetomidine is a high selective alpha2-adrenoceptor agonist. Mounting evidences show that dexmedetomidine-ropivacaine combination can also be used effectively for epidural labor analgesia. This pilot trial is designed to compare the effect of dexmedetomidine-ropivacaine combination versus sufentanil-ropivacaine combination on neonatal outcomes when used for epidural labor analgesia, and to test the feasibility of a future large randomized trial.

Sufentanil combined with ropivacaine is commonly used for epidural labor anesthesia. However, this combination is associated with some adverse events including increased risk of neonatal depression. Dexmedetomidine is a high selective alpha2-adrenoceptor agonist and possesses opioid-sparing and analgesic effects when used in combination with local anesthetics. Recently published data suggest that dexmedetomidine-ropivacaine combination can effectively relieve labor pain.

We suppose that, when compared with traditional sufentanil-ropivacaine combination, the dexmedetomidine-ropivacaine combination used for epidural labor analgesia may reduce sufentanil-related adverse neonatal outcomes. The purpose of this pilot trial is to compare the effect of dexmedetomidine-ropivacaine combination versus sufentanil-ropivacaine combination used for epidural labor analgesia on neonatal outcomes, and also to test the feasibility of a future large randomized trial.

Inclusion Criteria:

1. Aged 18-45 years;
2. Single term pregnancy with vertex presentation planning vaginal delivery;
3. Planning to receive epidural labor analgesia.

Exclusion Criteria:

1. Presence of contraindications to epidural analgesia, which includes: (1) History of infectious disease of the central nervous system (poliomyelitis, cerebrospinal meningitis, encephalitis, etc.); (2) History of spinal or intra-spinal disease (trauma or surgery of spinal column, intra-spinal canal mass, etc.); (3) Systemic infection (sepsis); (4) Skin or soft tissue infection at the site of epidural puncture; (5) Coagulopathy.
2. Existence of bradycardia (heart rate <60 bpm), hypotension (SBP <90 mmHg) or severe hypertension (SBP ≥180mmHg), uncontrolled systemic comorbidities (i.e., diabetes or hepatic, renal or cardiac disease), American Society of Anesthesiologists (ASA) physical status ≥3.
3. History of psychiatric disease or epilepsia.
4. Allergy to study agents.
5. Other conditions that are considered unsuitable for study participation.

All participants, attending anesthesiologists and other health-care team members, and outcome assessors are blinded to the study group assignment.