4 Discussion

The pelvic floor consists of muscles, ligaments, fascia, and nerves which maintain the integrity of the pelvic outlet and ensure urinary continence. The organs in the pelvic cavity include the urethra, bladder, uterus, fallopian tubes, vagina, and rectum, which rely on the pelvic floor tissue to maintain their normal anatomical positions. During vaginal delivery, the pelvic floor muscles are overstretched to 2.17 times the maximum length of normal pelvic floor muscles [1]. When the soft birth canal and the surrounding pelvic floor tissue are extremely dilated, the pelvic floor nerves, muscles, fascia, and ligaments will be impaired and may rupture [4]. The varying degrees of impairment, which might be reversible or irreversible, can result in structural and functional changes to the pelvic floor that lead to dysfunction of the pelvic floor [5].

The second stage of labor is accompanied by the most intense pressure on the tissue of the pelvic floor [6]. Previous studies have shown that increased duration of the second stage of labor could significantly increase the risk of the structural and functional impairment to the pelvic floor muscles [2,7]. The findings from the present study showed that there was no statistical difference in the duration of the second stage of labor among three groups and the mean duration of the second stage was 48.42 ​± ​30.2 ​min. Hands-off techniques in midwifery practice did not increase the duration of the second stage of labor without episiotomy, and this may be a more natural form of childbirth.

According to the characteristics of the pelvic floor muscle contraction, the muscles can be divided into TypeⅠand TypeⅡmuscle fibers. TypeⅠmuscle fibers mainly exist in the deep layers of levator ani muscles, and their physiological functions include tonic contractions and sustained contractions that are enduring and unlikely to cause muscle fatigue. TypeⅡmuscle fibers mainly exist in the superficial layers of perineal muscles, and their physiological functions include intermittent contractions, which are fast but tend to cause muscle fatigue. This study showed that there were no significant differences among the three groups in the impairment rate of TypeⅠand TypeⅡmuscle fibers (both, P ​> ​0.05), indicating that the three midwifery practices had almost the same effects on the pelvic floor muscle strength. However, a higher proportion of TypeⅠmuscle fibers were impaired than TypeⅡmuscle fibers, which may be explained by the fact that the volume and weight of the uterus would increase gradually after pregnancy, and the pelvic floor muscles would therefore be continuously stressed due to the influence of postpartum hormones [8], leading to greater impairment of TypeⅠmuscle fibers.

The results of this study showed that the incidence of urinary stress incontinence in the hands-off techniques midwifery practice group was significantly lower than in the lateral episiotomy group (P ​< ​0.05). The finding that hands-off techniques reduced the risk of postpartum urinary stress incontinence may be explained by the minimal use of episiotomy in this group. The bulbospongiosus muscle, the ischiocavernosus muscle, and the deep vaginal muscles and nerves can be impaired after lateral episiotomy, resulting in urinary stress incontinence [9]. In the hands-off technique group, the midwife’s hands will not routinely press against the perineal body, thus reducing the risks of edema and muscle impairment caused by continuous compression. Also, moderate control of the speed of delivery of the infant during childbirth would prevent perineal laceration caused by the uneven pressure in the vagina, which can reduce the risk of urinary stress incontinence [10,11]. Previous studies have shown that the incidence of postpartum urinary incontinence can be as high as 30%−60% [12]. Although hands-off technique can reduce the incidence of stress incontinence, it cannot be completely avoided because of the inevitable impact of vaginal delivery on the pelvic floor muscles. The rate of delivery of the infant disrupts the balance between the surrounding forces supporting the urinary tract. Therefore, it is necessary to actively perform functional training of the pelvic floor muscles after childbirth, and nurses should also provide health education on this for postpartum women.

A systematic review of the literature showed that the mode of delivery in primiparous women in China was an important factor in changes to the pelvic floor that were associated with postpartum sexual dysfunction [13]. Obstetric factors that may lead to muscle relaxation in the vaginal wall and the pelvic floor may impair female sexual function [14,15]. This study showed that the incidence of postpartum sexual dysfunction in the hands-off techniques group was lower than that in the lateral episiotomy group (P ​< ​0.01), but there was no significant difference between the hands-off techniques group and the traditional midwifery practice group. These findings indicate that lateral episiotomy may disrupt the integrity of the perineum and impair the important structures closely associated with female sexual function. Also, the large area of scar tissue caused by lateral episiotomy could impair sexual function to a certain degree [16]. In the hands-off techniques group and the traditional midwifery practice group, the continuity of the perineum was not disrupted. In addition, this postpartum sexual dysfunction survey also has limitations. Several factors also affect postpartum sexual dysfunction including the number of deliveries, breastfeeding, type of delivery, episiotomy, fatigue, and physical and psychological dysfunction including postpartum depression [17]. But what we need to take into consideration is that celibacy could cause many issues other than the pelvic floor-vaginal lubrication, lack of sleep and or desire. This remind us that comprehensive evaluation should be considered when using the questionnaire in future research.

With the increasing awareness of reproductive health care in developing countries, pregnant women and their families are paying more attention to the choice of delivery methods [18,19]. The World Health Organization issued a new guidance in Geneva on February 15, 2018, recommending the reduction of unnecessary medical interventions for healthy pregnant women. The lateral episiotomy incision artificially caused perineal damage, and it did not reduce the pain and perineal damage of the parturient. On the contrary, it caused postpartum problems such as wound healing difficulties, rectal injury and perineal scar re-injury. The hands-off techniques delivery can reduce the intervention of human factors to a certain extent, and strengthen the cooperation and cooperation between pregnant women and fetuses [20]. It can greatly reduce the damage to the mother’s body, help protect the integrity of the perineum, and reduce the discomfort such as pain, swelling, etc. Also, it can reduce the risk of neonatal asphyxia, improve pregnancy outcomes, ensure the safety of mothers and babies, make it easier for mothers to accept, and have higher satisfaction [21]. Therefore, the clinical application and promotion of the hands-off techniques delivery can be carried out in the future, while paying attention to the exact effect and long-term impact of the technology.