Pregnancy and childbirth are two important events in a women’s life. The two phases of life have been proved to be associated with increased incidence of PFDs. Pregnancy and childbirth, especially vaginal childbirth, are two independent factors causing PFDs [
8,
9]. Although severe morbidity of women from PFDs is rare, PFDs do seriously affect the quality of women’s life. At present China, permanent damage of PFM in older women has attracted much attention and lots of money have been invested on this issue. However, the prevention and treatment of PFDs during pregnancy and childbirth have not been attached with sufficient attention. The postpartum period is the time during which the PFM damage of women may develop into the most serious condition (fortunately it is reversible). If a woman in postpartum cannot persist on accepting conservation treatment (pelvic muscle exercise, electrical stimulation, and biofeedback, and so on) for postnatal PFDs, permanent PFDs will gradually come into being [
10,
11]. Paying attention to PFM damage and PFDs in recent postpartum period as well as finding effective method to guide restoration of pelvic floor function and improving the quality of women’s life are the direction of our efforts in the future.
At present, common detection methods of PFM strength include digital palpation, vaginal balloon, and surface electromyography (SEMG) and so on. Digital palpation can quantify the PFM strength directly, although it has always been questioned for its subjectivity. Vaginal balloon is more objective but not as precise as digital palpation. SEMG detects the electrical activity of PFM, yet its reliability in clinical application is still controversial. There is a strong correlation among the three methods in the assessment of the PFM strength [
12‐
14]. Digital palpation is mainly used in the census, while SEMG is normally used in evaluation of therapeutic effect of the PFM strength [
14]. In this study, through census of the PFM strength of women in postpartum 6–8 weeks, it can be known that the PFM strength of women having cesarean delivery is higher than that of women having vaginal delivery (including perineal laceration, episiotomy, and forceps assisted vaginal delivery), although t primiparas having cesarean delivery have older age, heavier baby’s weight and higher rate of GDM than those having vaginal delivery. This shows vaginal delivery is one of the important factors causing PFM damage in recent postpartum, which is consistent with results of previous researches [
15,
16]. This study shows that the PFM strength of primiparas having perineal laceration vaginal delivery is higher than that of primiparas having episiotomy vaginal delivery or forceps assisted vaginal delivery, which is mainly due to that the episiotomy may damage PFM and the integrity of pudendal nerve. It has always been a controversial topic to perform routine episiotomy on low-risk pregnant women during vaginal delivery [
17‐
19]. Supporters think that routine episiotomy can protect the anal sphincter [
18]. Opponents argue that routine episiotomy can increase the rates of postpartum bleeding, postpartum perineal incision infection, postpartum pain, urinary morbidity, and so on [
19]. Our study suggests that routine episiotomy cannot protect the PFM from being damaged. The PFM damage is also related with PFDs, therefore the effective measure to reduce and prevent PFDs on low-risk pregnant women is to protect the perineal integrity and do not perform routine episiotomy during vaginal delivery. Many studies show that operation vaginal delivery by forceps or vacuums significantly damage the PFM strength and increase the risk of PFDs during both the recent and long term postpartum period [
20‐
22]. But our study shows that there is no significant difference between episiotomy and forceps assisted vaginal delivery. This may be due to that the rate of forceps assisted vaginal delivery is very low in China, which is 1.51% (72/4769) in our hospital of primiparous women; for comparison, the percentage of operative vaginal delivery is 29.1% among primigrous women in Ireland [
23]. The fetal head position will be lower or outlet when using forceps, and some difficult forceps vaginal deliveries have been replaced by cesarean delivery in our hospital. Vaginal delivery is an independent risk factor leading to PFDs of primiparous women in short-time postpartum period. Although cesarean delivery reduces the risk of pelvic floor trauma, it is not entirely protective [
24]. Cesarean delivery is a protective delivery method for PFM of women in recent postpartum, but may be not useful for women in late postpartum [
17]. Moreover, cesarean delivery may easily bring other severe complications. Episiotomy may cause injury of PFM in low risk vaginal delivery or forceps vaginal delivery. We should try our best to reduce the rate of episiotomy in order to protect PFM in primiparous women.
The limitation of our study
Our study is subjected to a few limitations. Firstly, the modified Oxford score is very simple and is not sensitive enough to describe accurate change of PFM strength of the postpartum women. Another limitation is that palpation does not provide global assessment of the levator ani muscle which can be measured by techniques such as ultrasound imaging, MRI, a predefined protocol [
26], and so on. Lastly, due to lack of experience, it is difficult for postpartum women to properly cooperate with examination expert.
The high rate of cesarean delivery and low rate of operative vaginal delivery are the limitations of our study. In China, the high cesarean delivery rate is a social problem, nearly half of all newborns in China are delivered by cesarean approach [
27]. From January 2013 to January 2014, there were 13,490 cases of Chinese s primiparas delivered in our birth centre, the overall rate of cesarean delivery was 43.1%(5809/13490) and the overall rate of operative vaginal delivery was 1.6%(220/13490). Many operative vaginal deliveries were replaced by cesarean delivery, and the rate of maternal request cesarean delivery was nearly 10.0%(1351/13490). There was common preineum local block anesthesia before episiotomy but no neuraxial labor anlagesia for vaginal delivery.