Does Perineal Massage in Pregnancy Reduce the Levator Ani Muscle Co-activation?

The levator ani muscle has to relax instead of contracting during the pushing efforts in childbirth. However, some women consciously or unconsciously co-contract, or tighten, the levator ani muscle. This phenomenon is levator ani muscle co-activation. Recently, it has been shown that co-activation may be associated with unfavorable obstetric outcomes, such as prolonged second stages of labor and higher fetal head station in women with co-contraction.

Recently, a study assessing the correlation between levator ani muscle co-activation and perineal trauma has been published. This study found a significantly higher incidence of severe perineal trauma related to childbirth (i.e., third and fourth-degree lacerations and episiotomies) in women with levator ani muscle co-activation. This group of patients had approximately three times the risk of a vacuum-assisted vaginal delivery and five times the risk of developing a severe vagino-perineal laceration with potential involvement of the anal sphincter. Therefore, intervening in these patients with targeted measures to correct LAM co-activation in the third trimester of pregnancy might be promising.

Study design All women are informed about this study during the first trimester of pregnancy. During the anatomical scan, at 20-22 gestational weeks, women are screened for eligibility criteria, including: nulliparity, single pregnancy, fetus in cephalic presentation and fluency in Italian language. Women satisfying the inclusion criteria are asked to participate to this RCT. If women agree to participate in the study, an informed consent will be signed. Thereafter, a trans-perineal ultrasound will be performed in order to evaluate the presence of levator ani muscle co-activation. A medio-sagittal scan is obtained to identify the following landmarks: pubic symphysis, fetal head, rectum, and puborectal muscle. In this scan, the antero-posterior diameter of the anorectal angle (APD) is measured, which is the minimum distance between the postero-inferior border of the pubic symphysis and the anterior border of the puborectal muscle. This measurement is taken both at rest and during maternal pushing (Valsalva maneuver). Patients with co-activation will be identified by an APD during Valsalva that is smaller than the one observed at rest. Patients will be enrolled and randomized only in case of LAM co-activation.

A 1:1 randomization will be done using a specific function of Excel (preliminarily prepared by our Statistician). Women will be randomized in 2 arms: arm A is represented by the treatment "perineal massage", while arm B is represented by the "standard care".

At about 30 gestational weeks women randomized to arm A will be trained on how technically perform the perineal massage. Participants are instructed to do the perineal massage once daily from 34 gestational weeks until delivery, for at least 3 weeks continuously. By contrast, women randomized to arm B are informed on currently available recommendations to take care for pelvic floor in pregnancy. These recommendations include advices on healthy diet, physical activity and voiding training.