Urinary symptoms and pelvic floor muscle function during the third trimester of pregnancy in nulliparous women

To evaluate pelvic floor muscle (PFM) function and its association with urinary symptoms in the third trimester of pregnancy.

A cross-sectional study was conducted among 91 nulliparous women at 30-34 weeks of pregnancy. PFM was evaluated by surface electromyography (sEMG) and manual muscle testing, while urinary symptoms were identified by interview. Chi-square and Fisher's exact tests were used to analyze proportions and Mann-Whitney test was used to analyze differences in means.

Average sEMG values were 4.8 µV for basic tonus (BT), 19.2 µV for maximum voluntary contraction (MVC), and 12.9 µV for average sustained contraction (ASC), and 48.4% presented muscle strength grade 3. Nocturia was reported by 80.2%, followed by increased daytime frequency (59.3%), stress urinary incontinence (50.5%), and urge urinary incontinence (25.3%). No association was found between urinary symptoms and MVC or ASC or PFM manual tested strength.

No association was observed between PFM function and urinary incontinence, except decreased BT among late third trimester pregnant women with irritative bladder symptoms.