Evaluation of perineal muscle strength in the first trimester of pregnancy

OBJECTIVES: to analyze the Pelvic Floor Muscle Strength (PFMS) of pregnant women with one or more vaginal or cesarean deliveries; to compare the PFMS of these with pregnant women with the PFMS of primiparous women. METHODS: cross-sectional study with women up to 12 weeks pregnant, performed in Itapecerica da Serra, São Paulo state, from December 2012 to May 2013. The sample consisted of 110 pregnant women with one or more vaginal deliveries or cesarean sections and 110 primigravidae. The PFMS was evaluated by perineometry (Peritron(tm)) and vaginal digital palpation (modified Oxford scale). RESULTS: the average PFMS in pregnant women with a history of vaginal delivery or cesarean section was 33.4 (SD=21.2) cmH2O. From the Oxford scale, 75.4% of the pregnant women with previous vaginal or cesarean deliveries presented grade ≤ 2, and 5.5% grade ≥ 4; among the primiparae, 39.9% presented grade ≤ 2, and 50.9% grade ≥ 4, with a statistically significant difference (p<0.001). From the perineometry, there was no statistically significant difference between the PFMS and age, type of delivery, parity, body mass index, and genitourinary tract symptoms, however, there was a statistically significant difference between the pregnant women with and without a history of episiotomy (p=0.04). In the palpation, none of the variables showed a statistically significant difference. CONCLUSION: pregnancy and childbirth can reduce the PFMS.


Introduction
The pregnancy, type of delivery, perineal conditions, and parity may influence the pelvic floor muscle strength (PFMS), causing morbidities of the genitourinary urinary tract and a negative effect in relation to the sexual, physical, psychological, and social health of the woman (1)(2) .
A study that evaluated the quality of life in 77 women with urinary incontinence (UI) 90 days after childbirth identified the most common symptoms as: micturition frequency (88.3%), nocturia (87%) and urge incontinence (54.5%). The authors concluded that although the loss of urine was small, it was frequent and caused an impact in the life of the women, interfering significantly in their physical and mental health (3) .
Regarding parity, a cohort study identified an increased prevalence of UI that remained for one year after delivery, among primiparae, compared to women with no previous births (4) .
A prospective cohort study, conducted with 110 primiparae, compared the means of PFMS during the pregnancy and after delivery, using perineometry and vaginal digital palpation. These primiparae were followed at four moments: up to 12 weeks of gestation; between 36 and 40 weeks of gestation; between 42 and 60 days after the delivery. The results showed that the PFMS did not change significantly during the pregnancy nor in the puerperium (ANOVA: p =0.78), with a prevalence of weak intensity PFMS. The study also found that there was no statistically significant difference in relation to maternal age, race, marital status, dyspareunia, nutritional status, stool characteristics, type of delivery, perineal conditions, and weight of the newborn (5) .
There are several studies on PFMS and genitourinary symptoms from the second half of pregnancy and after childbirth, however, there are few data related to the first trimester. Nevertheless, it is considered important to know the conditions of the pelvic floor (PF) when a woman starts pregnancy because the literature indicates the efficacy of prevention and early treatment of UI, the principle genitourinary symptom, through perineal exercises (6) . The sample consisted of 110 pregnant women. This is the same sample size defined in an earlier study of 110 primigravidae with the same inclusion and exclusion criteria (5) , which were considered to be the historical controls for comparison with the pregnant women in this study.
Data were collected by two previously trained researchers and all the participants underwent measurement of the PFMS by perineometry and vaginal digital palpation.
It is noteworthy that in the study with the primigravidae (historical control) only one researcher measured the vaginal digital palpation. In the present study, the same researcher was one of the two who performed the PFMS evaluation. However, concordance between the examiners was not analyzed.
To avoid bias in the data, a table was produced for the random application of the sequence of PFMS measurement methods, using a statistical program.
Accordingly, the perineometry could be performed first and then the vaginal digital palpation, or vice versa.   Table 1 shows the comparison between the sociodemographic  In the vaginal digital palpation, none of the variables analyzed showed a statistically significant difference. It is noteworthy that there was no grade ≥ 4 among the women in the extreme age groups, those with four or more deliveries or those with obesity. Accordingly, the proportion of pregnant women with grade ≥ 4 was higher among those without genitourinary tract symptoms, compared to those who reported these symptoms.
Although not statistically significant, the women who had undergone episiotomies had higher grades in the Oxford scale, considering the degrees above 2 (26.1% with episiotomy vs. 13.3%, without).   In the present study, this PFM weakness was more frequent among women with one or more previous cesarean or vaginal deliveries, compared with the primigravidae historical control (5) , reinforcing the impact in the PF muscles caused by pregnancy and delivery.

As shown in
Regarding the perineometry, the interpretation and comparison with other studies may be hampered by the diversity of equipment and methods used in the evaluation (8)(9)(10)(11)(12) . For this reason, the perineometry values obtained for the historical controls (5) could not be used in this study due to the use of a Perina 996-2 ® perineometer, with a scale ranging from 1.6 to 46.4 mmHg and a mean obtained of 15.9 mmHg among 110 primigravidae in the first trimester of pregnancy (5) ; this corresponds to a weak contraction (8) .
As stated in the method, the perineometer adopted in this study was the Peritron TM 9300, with a scale ranging The study aimed to investigate the obstetric, neonatal and clinical predictors for UUI and used the perineometer of this study showing that a PFMS ≤ 35.5 cmH 2 O was the strongest predictor of UUI (13) .
Another study that evaluated genitourinary tract symptoms in 120 women three years after childbirth concluded that the pregnancy is more related to UUI than the delivery (14) . Conversely, these genitourinary tract symptoms can be prevented or improved through strengthening of the PFM through exercises (15) .
The women in the present study were in the first Regarding the PFMS and genitourinary tract symptoms, maternal age and BMI showed no statistically significant difference, as in other studies (5,10,15) . However, researchers have found that these variables can have an impact on the PFMS (16)(17) . Urinary and anal incontinence may be associated with damage to the PF muscles caused by vaginal delivery (18 (20) .
Another study (21)  These results differ from those obtained in other studies as well as those from the systematic review of six randomized controlled trials, as their results showed that the restricted use of episiotomy reduces morbidity of the PF muscles (22)(23) .
In the present study, it is should be noted that the population was young, of reproductive age without hormonal changes caused by the menopause or other adverse effects of advanced age on the PF muscles.
However, according to the vaginal digital palpation, the PFMS was below that expected and considered normal and strong (grades 4 and 5 of the Oxford scale) (7)(8) .
There are several factors that can influence the PFMS and, although the decrease that occurs in every pregnancy or delivery is not always significant, over several pregnancies and deliveries, this decrease can become significant (5) .
Accordingly, it is important that genitourinary tract symptoms are considered during the prenatal and postpartum periods and that, with the occurrence of morbidities, monitoring and effective treatment is performed, so that this will not interfere in the choice of delivery method and that women are not discouraged from becoming pregnant.
Several studies have shown that perineal exercises during pregnancy are a safe and effective method for maintaining urinary continence, both for women with a history of UI, as well as for those without urinary leakage (14,24) .
There was good acceptance by the pregnant women to participate in the study considering that, although the measurement of PFMS is not a painful procedure, it can cause embarrassment and discomfort. They were guided and encouraged to perform exercises to strengthen the PF muscles.
Regarding the perineum conditions during delivery i.e., episiotomy, spontaneous lacerations or tissue integrity, prospective studies, with monitoring of the women from before the first pregnancy until a long period after the birth, could help to evaluate its real impact on the PF muscles.

Conclusion
The PFMS of the majority of the pregnant women was classified as weak in the first trimester of the pregnancy.