Electromyographic activity of the pelvic floor muscles in the third trimester: comparison between primigravidae and secundigravidae

The objective was to compare the electromyographic activity of pelvic floor muscle (PFM) on third semester between primigravidae and secundigravidae who had previous vaginal delivery. Cross-sectional observational study. Nineteen primigravidae and 21 secundigravidae between 34'h and 361 gestational weeks were evaluated. Data collection consisted in assessing the PFMs activity by surface electromyography. The variables related to electromyographic assessment such peak and average on the rest, maximal voluntary contraction, and sustained contraction. There were no differences on electromyographic activity of PFMs between primigravidae and secondigravidae. However, a significant increase in body mass index and a negative correlation of the newborn weight with the peak value of electromyographic signal during maximal voluntary contraction were observed. The factors that can change the electromyographic activity pattern during pregnancy can be related to maternal body mass increased and newborn weight.