The purpose of this study is to observe the appropriate indwelling depth of epidural catheter when labor analgesia is performed in the mode of DPE combined with PIEB, and then shorten the onset time of labor analgesia and reduce the occurrence of catheter-related adverse outcomes.
Those aged 18 to 45 years old;
Pregnancy lasts for 37 to 42 weeks;
Single healthy pregnant women with cervical dilation < 3.0 cm who wish to use epidural labor analgesia;
The NRS score of uterine contraction pain is > 3;
Those with contraindications to intraspinal anesthesia;
Those with a history of allergy to local anesthetics and opioids;
Pregnancy diseases (such as pregnancy-induced hypertension, preeclampsia or gestational diabetes, etc.);
Known fetal abnormalities or situations associated with an increased risk of cesarean section;