Introduction: The objective of these clinical practice guidelines was to analyse all of the interventions during pregnancy and childbirth that might prevent obstetric anal sphincter injuries (OASIS) and postnatal pelvic floor symptoms.Material and methods: These guidelines were developed in accordance with the methods prescribed by the French Health Authority (HAS).Results: A prenatal clinical examination of the perineum is recommended for women with a history of Crohn's disease, OASIS, genital mutilation, or perianal lesions (professional consensus). Just after delivery, a perineal examination is recommended to check for OASIS (Grade B); if there is doubt about the diagnosis, a second opinion should be requested (Grade C). In case of OASIS, the injuries (including their severity) and the technique for their repair should be described in detail (Grade C). Perineal massage during pregnancy must be encouraged among women who want it (Grade B). No intervention conducted before the start of the active phase of the second stage of labour has been shown to be effective in reducing the risk of perineal injury. The crowning of the baby's head should be manually controlled and the posterior perineum manually supported to reduce the risk of OASIS (Grade C). The performance of an episiotomy during normal deliveries is not recommended to reduce the risk of OASIS (Grade A). In instrumental deliveries, episiotomy may be indicated to avoid OASIS (Grade C). When an episiotomy is performed, a mediolateral incision is recommended (Grade B). The indication for episiotomy should be explained to the woman, and she should consent before its performance. Advising women to have a caesarean delivery for primary prevention of postnatal urinary or anal incontinence is not recommended (Grade B). During pregnancy and again in the labour room, obstetrics professionals should focus on the woman's expectations and inform her about the modes of delivery.

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An assessment of the elastic properties of the levator ani muscles is feasible for nonpregnant women. The reproducibility of the technique and its application in pregnant women and women with pelvic floor disorders must be investigated.

Does the implementation of a restrictive episiotomy policy for operative deliveries increase the risk of obstetric anal sphincter injury?. Abstract: 250 words 6 Main text: 3.054 words 7 8 ABSTRACT: 250 words 44 45 Purpose 46 Our main objective was to investigate whether the implementation of a restrictive 47 72 73 74 Title: Does the implementation of a restrictive episiotomy policy for operative deliveries 75 increase the risk of obstetric anal sphincter injury? 76 MAIN TEXT: 3.054 words 77 78

Background: Animal studies have reported an increase in pelvic floor muscle stiffness during pregnancy, which might be a protective process against perineal trauma at delivery. Our main objective is to describe the changes in the elastic properties of the pelvic floor muscles (levator ani, external anal sphincter) during human pregnancy using shear wave elastography (SWE) technology. Secondary objectives are as follows: i) to look for specific changes of the pelvic floor muscles compared to peripheral muscles; ii) to determine whether an association between the elastic properties of the levator ani and perineal clinical and B-mode ultrasound measures exists; and iii) to provide explorative data about an association between pelvic floor muscle characteristics and the risk of perineal tears. Methods: Our prospective monocentric study will involve three visits (14-18, 24-28, and 34-38 weeks of pregnancy) and include nulliparous women older than 18 years, with a normal pregnancy and a body mass index (BMI) lower than 35 kg.m − 2. Each visit will consist of a clinical pelvic floor assessment (using the Pelvic Organ Prolapse Quantification system), an ultrasound perineal measure of the anteroposterior hiatal diameter and SWE assessment of the levator ani and the external anal sphincter muscles (at rest, during the Valsalva maneuver and during pelvic floor contraction), and SWE assessment of both the biceps brachii and the gastrocnemius medialis (at rest, extension and contraction). We will collect data about the mode of delivery and the occurrence of perineal tears. We will investigate changes in continuous variables collected using the Friedman test. We will look for an association between the elastic properties of the levator ani muscle and clinical / ultrasound measures using a Spearman test at each trimester. We will investigate the association between the elastic properties of the pelvic floor muscles and perineal tear occurrence using a multivariate analysis with logistic regression. Discussion: This study will provide original in vivo human data about the biomechanical changes of pregnant women's pelvic floor. The results may lead to an individualized risk assessment of perineal trauma at childbirth. Trial registration: This study was registered on https://clinicaltrials.gov on July 26, 2018 (NCT03602196).