Vaginal delivery is considered a risk factor for developing urinary incontinence, anal incontinence, and pelvic organ prolapse – dysfunctions closely related to pelvic floor muscles (PFMs) [1]. Several intrapartum risk factors have been mentioned in available literature: instrumental vaginal delivery, spontaneous vaginal delivery, episiotomy, tears, oxytocin augmentation, and birthweight over 4000 g [2]. However, previous studies were focused on longer-term observations, and currently, we have limited data regarding PFMs function early postpartum. What is more, to our knowledge, associations between PFMs function shortly after delivery and intrapartum factors were not previously investigated. Therefore, this study aimed to assess the PFMs function in primiparous women 24-72h after vaginal delivery and to examine whether there are any associations between intrapartum characteristics and PFMs function shortly postpartum.

This retrospective cohort study included medical records from PFMs physiotherapy assessments performed 24-72h postpartum as a part of standard care in our hospital. Primiparous women after vaginal delivery (gestation week 36 or more) were included in this analysis. During vaginal examination, the following PFMs parameters were assessed: (1) PFMs strength - maximal voluntary contraction assessed with Modified Oxford Scale (0-5); (2) PFMs endurance measured in seconds (0-10 seconds); (3) correctness of the contraction (yes/no; isolated PFMs activation without breath holding was considered correct); and (4) PFM tone assessed with Reissing scale (7-level grade ranging from -3 hypotonic to +3 hypertonic). Intrapartum characteristics included: duration of the second stage of labor, neonatal birth weight, fetal positioning (occiput anterior, occiput posterior, sinciput, brow), uterine contractile activity (spontaneous, stimulated, induced), epidural anesthesia (yes/no), degree of perineal tear (1st, 2nd, 3rd, 4th degree) and episiotomy (yes/no). To assess the relationship between the intrapartum characteristics and PFMs function, general linear models (PFMs strength, tone, and endurance), and a logistic regression model (correctness of contraction) were used. All analyses were adjusted for age and weight gain during pregnancy. Values of p < 0.05 were considered significant.

Records of 856 women with mean age of 30.2 ± 4.3 years were included in this study. Among the assessed participants, 96.6% (n=827) were able to voluntarily contract PFMs, and 73.8% (n=610) performed it correctly (in an isolated manner, without breath-holding). The mean strength of pelvic floor muscles was 2.02 ± 0.82 on Modified Oxford Scale and the mean endurance was 4.26 ± 2.36 seconds. The mean observed muscle tone assessed with the Reissing scale was -0.09 ± 0.56. Results of multivariable analysis adjusted for age and weight gain during pregnancy showed that episiotomy was associated with a lower likelihood to correctly activate the PFMs (OR 0.70, CI 0.49 – 0.99). Higher values of neonatal birth weight and birth weight over 4000 g were associated with lower grades on the Reissing scale (β -0.0001, p=0.01, and β -0.18, p=0.02, respectively). No other statistically significant associations were observed.

This research contributes to the limited knowledge of PFMs function in the early postpartum period. Presented results showed that women can activate PFMs regardless of being shortly after vaginal delivery and rates of correct activation are similar to those in the general population [3].To our knowledge, this is the first study that examines the association between intrapartum characteristics and specific variables of PFMs function within the first days following vaginal delivery. Our results indicated that episiotomy and neonatal birth weight may be independently associated with decreased ability for correct PFMs activation and lower PFMs tone shortly postpartum.

High rates of ability to activate PFMs may suggest that women can efficiently exercise PFMs already in the early postpartum period. Special attention should be paid to PFMs muscle tone in women delivering heavier newborns and to the ability to correctly activate PFMs in those who received episiotomy. Further prospective studies are needed to determine if these trends in PFMs changes persist over time, contributing to a greater risk of developing pelvic floor dysfunction. This could possibly indicate which variables should be specifically targeted during pelvic floor physiotherapy in women with particular intrapartum characteristics.

Hallock JL, Handa VL. The Epidemiology of Pelvic Floor Disorders and Childbirth: An Update. Obstet Gynecol Clin North Am. 2016 Mar;43(1):1-13
Hage-Fransen MAH, Wiezer M, Otto A, Wieffer-Platvoet MS, Slotman MH, Nijhuis-van der Sanden MWG, Pool-Goudzwaard AL. Pregnancy- and obstetric-related risk factors for urinary incontinence, fecal incontinence, or pelvic organ prolapse later in life: A systematic review and meta-analysis. Acta Obstet Gynecol Scand. 2021 Mar;100(3):373-382.
Henderson JW, Wang S, Egger MJ, Masters M, Nygaard I. Can women correctly contract their pelvic floor muscles without formal instruction? Female Pelvic Med Reconstr Surg 2013; 19(1): 8-12.