Levator Ani Muscle (LAM) avulsion occurs in 13-36% of women having their first birth. These damages by palpation and ultrasound of the pelvic floor can be detected. Avulsion of the LAM results in decreased muscle strength of the pelvic floor, enlarge the genital hiatus and promotes pelvic organ prolapse. The perineal muscle training is a proposal to combine the perineal massage with pelvic floor exercises in order to prepare the LAM in the last weeks before delivery, to withstand stretching which will be submitted during childbirth. No studies in the world that have explored the effect of the perineal muscle training on the avulsion of MEA.

Objective: To quantify the proportion of primiparous that result with avulsion of LAM after their first birth among those performing perineal muscle training from week 33 of gestation and those with usual prenatal care.

This study will be performed in 228 primiparous. Previous informed consent they will be randomized in two groups: 1) perineal muscle training and 2) usual prenatal care. Pelvic floor will be evaluated before and after childbirth clinically and ultrasonographilly. The outcome variables will be: 1) avulsion LAM diagnosed by palpation and 2-3D pelvic floor ultrasound, 2) symptoms of pelvic floor dysfunction identified with standardized and validated Spanish PFDI-20 questionnaire, 3) changes dimension of the genital hiatus and perineal body, 4) accomplishment of perineal muscle training. Demographic variables (marital status, occupation, level of education, age, weeks of gestation, weight, height, BMI, religion, pathologies) and variables related to childbirth (weeks of gestation duration of the second period, use of analgesia, variety of position, episiotomy, forceps. dystocia, who attended the birth, weight and head circumference of the newborn, tearing report and who repairs the last one.

Inclusion Criteria:

1. Future primiparous over 18 who have single fetus, without contraindications to take delivery. Primigesta omit the term since in the study patients who have had previous pregnancies that are not related to damage to the pelvic floor as will be accepted: abortions, ectopic or molar.
2. With or without symptoms of pelvic floor dysfunction (assessed with PFDI-20 questionnaire).
3. Have 33 weeks gestation to start participating, so the invitation must be made before this gestational age as mentioned above.
4. Physical and mental ability to understand and perform the maneuvers used in the study.

Exclusion Criteria:

1. Any contraindication to labor, this feature can appear at any time during pregnancy, including during labor.
2. Physical or mental inability to perform the maneuvers used in the study.
3. Avulsion of MEA detected before birth.
4. Agree not participate in the study.
5. Previous pregnancies older than 20 weeks gestation resolved abdominally.