Combined spinal-epidural analgesia (CSEA) is sometimes used for difficult births, but whether it contributes to postpartum pelvic muscle disorder is unclear. This randomized controlled trial examined whether CSEA affects the electrophysiological index of postpartum pelvic floor muscle during labor. The investigators plan to recruit 300 primiparous healthy women.

Labor analgesia can relieve labor pain, reduce stress reactions, and improve blood supply to the fetus, benefiting mother and baby. Though traditional epidural analgesia has been used for more than 40 years, combined spinal-epidural analgesia (CSEA) has become popular because it provides faster-onset pain relief with minimal motor weakness. CSEA may also accelerate cervical dilation.

Despite the popularity of CSEA, whether it is associated with short- or long-term beneficial or adverse effects on mothers remains unclear. One question is whether the procedure affects the risk of female pelvic floor disorder (PFD), in which the pelvic floor muscles are injured. These muscles are responsible for supporting the pelvic organs and for stabilizing them during the rhythmic, strong labor contractions and for the diaphragm to contract enough to generate pressures of up to 19 kPa. Numerous risk factors have been associated with PFD, including obesity, diabetes, older age, connective tissue disorder, neurological disease, pregnancy, vaginal delivery and childbirth. PFD can lead in turn to stress urinary incontinence, overactive bladder, pelvic organ prolapse and fecal incontinence, all of which can strongly reduce women's physical and psychological health.

Pelvic floor function can be analyzed by measuring the strength and degree of fatigue of pelvic floor muscles, as well as the pelvic dynamic pressure. Abnormalities in these indicators appear even before patients complain of the signs and symptoms of PFD, making them a useful early diagnostic index.

In this randomized controlled study, we examined whether CSEA affects postpartum pelvic floor muscle function in primiparous mothers who give birth vaginally, as well as the duration of different stages of labor. Our results should help establish whether the widespread use of CSEA provides benefits to mothers or poses a risk.

Inclusion Criteria:

• Primiparous women gave birth by vaginal delivery between June 2013 and June 2014 in the Maternal and Child Health Hospital of Nanning
• They were 22-30 years old
• They were 155-165 cm tall
• They were assigned a score of I or II on the American Society of Anesthesiologists scale
• They gave birth by vaginal delivery to a live, single, mature fetus (≥ 38, ≤ 40 w) in the head position
• A neonatal weight of 2900-3500 g

Exclusion Criteria:

• History of chronic cough
• Chronic constipation or pelvic organ resection
• Family history of urinary incontinence
• Pelvic organ prolapsus
• Any systemic disease before delivery
• A history of surgery, trauma, tumors or deformity of lumbar vertebrae