Effects of the Oxytocin Hormone on Pelvic Floor Muscles in Pregnant Rats.

Background and Objectives: Oxytocin induction is a known risk factor for pelvic floor disorders (PFDs). The aim of the study was to investigate the effects of oxytocin induction on pelvic floor muscles in pregnant rats. Methods: Thirty-two female Wistar rats were included and divided into four groups (n = 8). The groups were as follows: virgin group (group I)-from which muscles were dissected at the beginning of the experiment; spontaneous vaginal delivery (group II) which has delivery spontaneously; saline control group (group III) and oxytocin group (group IV). In groups III and IV, pregnancy was induced on d 21 of pregnancy, with 2.5 mU saline solution or iv oxytocin, respectively, delivered by the intravenous (iv) route in pulses at 10-min intervals for 8 h. Then, the rats were euthanized, the m. coccygeus, m. iliocaudalis and m. pubocaudalis muscles were excised and tissue samples were taken. After histological processing, the vertical and horizontal dimensions of the muscles were analyzed under a light microscope. Results: In group IV; the measurement of the horizontal dimension of the m. pubocaudalis muscles was 50.1 ± 5.4 µm and it was significantly higher than other groups (p < 0.001). In group III; the mean value of the horizontal dimension of m. coccygeus muscle was found to be 49.5 ± 10.9 µm and it was significantly higher than other groups (p < 0.009). Between-group comparisons revealed no difference in mean m. iliocaudalis muscle dimension (p > 0.05). Conclusions: As a result of our study it can say that whether oxytocin induced or not, vaginal birth is a process that affects the pelvic muscles.