The hidden power in the miracle of pregnancy: the effect of pelvic floor muscle training on fetal and fetal-maternal blood circulation and pelvic floor muscles during pregnancy, a randomized controlled trial

Abstract

Background

This study aimed to evaluate the effects of individualized pelvic floor muscle training (PFMT) in pregnant women on clitoral artery, umbilical artery (UmA), middle cerebral artery (MCA), uterine artery (UA) blood flow, and pelvic floor muscle (PFM) function.

Methods

Forty-seven primiparous women between 20 and 38 weeks of gestation were included in the study. Participants were randomly divided into exercise (n = 23) and control (n = 24) groups. The exercise group received an individualized PFMT home program, while the control group received standard antenatal care. Blood flow measurements of the clitoral, UmA, MCA, and UA were performed with Doppler ultrasonography (USG) in both groups. Additionally, PFM function was assessed by digital palpation using the PERFECT system and USG. Measurements were repeated three times at 20–24, 28–32, and 35–38 weeks of gestation.

Results

A statistically significant increase was observed in PFM endurance and fast twitch values in the PFMT group (p < 0.001). No statistically significant difference was found between the groups in the pulsatility indices (PI) of the clitoral, UmA, MCA, and UA at three time points (p > 0.05). However, as pregnancy progressed, UmA PI decreased more in the exercise group (p = 0.004). The time-dependent change in the MCA/UmA PI ratio was not statistically significant across groups (p = 0.075). A Generalized Estimating Equations (GEE) model was used to evaluate the significance of main effects for group, time, and their interaction (group × time).

Conclusion

PFMT during pregnancy has positive effects on the PFM function and may play a modulating role in the maternal and fetal circulatory systems. Specifically, the positive changes observed in UmA blood flow support the potential benefits of PFMT for fetal well-being. Therefore, we believe recommending PFMT to pregnant women in clinical practice has the potential to enhance their quality of life and support a healthy pregnancy journey. However, more comprehensive, long-term postnatal follow-up studies are needed to definitively confirm PFMT’s long-term effects on fetal neurodevelopment.

Trial registration

: NCT06861335, 02/28/2025 (retrospectively registered).

Background

Pregnancy is a period of critical physiological changes for the health of both the mother and the fetus. Regular and supervised exercise is recommended during this period due to its proven benefits [1]. Numerous studies in the literature indicate that physical activity and exercise not only support maternal health but also significantly reduce the incidence and severity of pregnancy complications such as preeclampsia and gestational diabetes, improve maternal cardiovascular function, control weight gain and fat retention, and improve insulin resistance [2–4].

During pregnancy, significant loads and adaptations occur in the maternal organism, particularly on the musculoskeletal system [5]. Factors such as changes in the center of gravity, mechanical stress, hormonal fluctuations, joint laxity, weight gain, and postural adaptations also lead to changes in the abdominal and pelvic regions [5, 6]. With the progression of pregnancy, the increasing weight of the fetus and uterus places a significant load on the bladder, urethra, and pelvic floor muscles (PFM) [7, 8]. A decrease in muscle tone and weakening of the PFM may be observed along with hormonal changes [7]. This condition can negatively affect the function of the PFM, leading to various dysfunctions [9].

The positive effects of pelvic floor muscle training (PFMT) on pregnant women are supported by a high level of evidence in the literature. Pregnancy and the birthing process, especially obstetric interventions (e.g., delivery with forceps or vacuum), are significant factors that can cause damage to the pelvic floor tissue. PFMT has been shown to facilitate the birthing process, reduce severe perineal tears, and shorten the second stage of labor [10]. Due to the lack of adverse effects of PFMT on the fetus and the proven benefits for mothers, it is recommended during pregnancy, especially for the prevention or treatment of urinary incontinence [11, 12]. Additionally, PFMT can prevent venous stasis by increasing blood circulation in the pelvic region in pregnant women [13]. Studies have shown that 4–12 weeks of skeletal muscle training increases blood flow in the arteries of the trained muscles both at rest and after activation [14]. Since the PFM arteries also supply blood to the vulvovaginal tissues, PFMT may improve blood flow in these tissues [15].

Studies have shown that a regularly supervised moderate-intensity exercise program during pregnancy does not negatively affect fetal or maternal ultrasound Doppler parameters [16], that exercise in women with normal pregnancies or gestational diabetes has no adverse effects on fetal heart rate, hyperthermia, neonatal morbidity, or mortality [17, 18], and that maternal exercise reduces the risk of macrosomia [19]. Furthermore, a study on pregnant mice showed that maternal exercise supports placental angiogenesis, branching, and blood flow in both healthy and obese pregnant mice [20]. However, as with general exercises, how the redirection of blood flow from internal organs to muscles during pelvic floor exercises [21, 22] and how fetal well-being may be affected by this redistribution are still not fully understood. A recent systematic review evaluating the effect of regular maternal physical activity, including pelvic floor exercises, on fetal and newborn well-being in uncomplicated pregnancies, including studies evaluating fetal Doppler in routinely exercising pregnancies, concluded that although it appears safe, the scientific evidence is heterogeneous and insufficient [23]. Since exercise during pregnancy can affect maternal and fetal hemodynamics [12], the evaluation of fetal well-being and hemodynamic parameters with Color Doppler ultrasonography (USG) is important, especially in pregnant women undergoing pelvic floor exercises [16, 24]. Examinations of the uterine artery (UA) and umbilical artery (UmA) provide information about uteroplacental and fetoplacental perfusion, while fetal middle cerebral artery (MCA) CDUS examination helps in determining the hemodynamic responses to fetal hypoxia [25].

The distinct differences observed between PFMT and other types of exercise raise the potential for PFMT to elicit atypical hemodynamic effects. The close anatomical relationship and shared vascular supply of the PFM with the uterus may potentially cause changes in uteroplacental and fetal circulation. Therefore, considering the proven benefits of PFMT for pregnant women, the scientific evaluation of the safety of this practice for the fetus is critically important. The primary aim of the present study is to investigate the chronic effects of PFMT on vulvovaginal, UA, UmA, MCA blood flow, and PFM muscle function using Doppler USG.

Methods

This prospective study, registered at ClinicalTrials.gov (NCT06861335) and conducted in accordance with the Helsinki Declaration with ethical approval (2024/43 − 27), enrolled primiparous pregnant women (≥ 18 years, ≥ 20th gestational week, singleton pregnancy) presenting to the Obstetrics and Gynecology Department of XXX University Faculty of Medicine Hospital. All participants provided informed consent after receiving detailed information about the study’s purpose and evaluation methods. Exclusion criteria included multiple pregnancies, pre-existing pregnancy-related complications (hypertension, preeclampsia, gestational diabetes, etc.), obstetrician-defined high-risk status, risk of preterm birth/early delivery/miscarriage, neurological or psychiatric diagnoses, severe cognitive impairment, and debilitating low back pain. This research followed the CONSORT guidelines.

Study design, randomization, and blinding

This was a controlled clinical trial using a 1:1 randomized allocation to two parallel groups. Before any measurements, we recorded participants’ socio-demographic characteristics (age, sex, height, weight, body mass index, education level, occupation, marital status) and their medical, obstetric, and gynecological histories.

For data collection, we assessed PFM strength through digital palpation using the PERFECT Scale and USG. Vulvovaginal blood flow was evaluated with clitoral Doppler ultrasound. During routine pregnancy check-ups, we also measured UmA, UA, and middle MCA blood flow via Doppler ultrasound. All these assessments were performed three times in total, starting from the second trimester and coinciding with routine doctor visits: the first at 20–24 weeks of gestation, the second at 28–32 weeks, and the third at 35–38 weeks.

After baseline data collection, participants were randomly assigned to either the Exercise Group (EG: n = 23) or the Control Group (CG: n = 24). We used a computer-generated block randomization method, executed by an independent researcher not involved in the study team, via IBM SPSS v.26 software.

To ensure allocation concealment, a third party, completely independent of the researchers assessing participants, securely held the randomization list. Group assignments were communicated only after each new participant was identified, using sealed, sequentially numbered envelopes whose contents remained unknown until opened.

In our study, the biostatistician performing the statistical analyses and the outcome assessors were kept blind to group assignments.

Assessments

Evaluation of PFM and endurance by digital palpation

Clinical assessment of PFM strength often involves palpation of vaginal contraction around inserted fingers, with the Modified Oxford Grading Scale, a common tool attributed to Laycock, used for categorization. Although reliable and valid for intra-rater measurements, its inter-rater reliability and validity are limited [26]. The PERFECT Scale, developed by Laycock in 2001 [27], offers a more comprehensive evaluation, assessing Power (P) of voluntary contraction, Endurance (E), slow-twitch fiber function (R), fast-twitch fiber function (F), PFM contraction pattern (E), transversus abdominis co-contraction (C), and involuntary response to increased intra-abdominal pressure (T) [28].

USG procedures

Participants underwent transperineal and abdominal ultrasound examinations while supine on a gynecological examination chair with semi-flexed and abducted knees and hips. Prior to the procedure, participants emptied their bladder and bowel and received thorough instruction on PFM contraction. Throughout the assessment, the ultrasound transducer remained stationary, and all EMG and USG measurements were consistently taken from the right side of the body, which was the dominant extremity for all participants.

Levator hiatal area (LHA) USG

3D/4D transperineal ultrasound of the pelvic floor was performed by one of two experienced clinicians using a Voluson S8 device (GE Healthcare, Korea) with a RAB 4–8-MHz curved array transducer (85° acquisition angle). Midsagittal plane volumes were recorded from rest to maximum PFM contraction. Rendered 3D volumes facilitated the measurement of the levator hiatal supero-inferior and medio-lateral diameters and area (defined by the pubovisceral muscle, pubic symphysis, and inferior pubic ramus) at rest, during contraction, and during Valsalva maneuver. The reliability of these measurements has been previously established in this population [29, 30].

Blood flow assessment

Clitoral doppler USG

A Voluson E8 system (GE Healthcare, Salzburg, Austria) was used to identify the dorsal clitoral artery in a longitudinal plane, sampled from the clitoral body’s outer surface. Similarly, the terminal branch of the posterior labial artery (a branch of the internal pudendal artery) was visualized posterolaterally to the labia majora (approximately 2 cm from the clitoral hood). For both arteries, the insonation angle was consistently adjusted to < 40° for optimal color Doppler signal. Pulsed Doppler mode was then activated to record blood flow velocity waveforms, with the spectral Doppler gate positioned along the vessel. The Systolic/Diastolic (S/D) ratio and Pulsatility Index (PI) were automatically calculated as the difference between peak systolic and end-diastolic flow divided by the mean maximum flow velocity. The average of three consecutive waveforms was used for analysis [31].

Khalifé’s Procedure for Pubic Vascular Assessment: A 4–13 MHz linear probe was placed on the pubis with the participant in a supine, knee-bent position [32]. The initial blood flow image on the ultrasound screen was recorded. Pulsed Doppler mode was used to collect five parameters: peak systolic velocity, time-averaged maximum velocity, end-diastolic velocity, PI, and resistance index (RI). Peak systolic velocity represents the maximum blood flow velocity during ventricular contraction, while end-diastolic velocity reflects flow velocity at the end of ventricular relaxation. Time-averaged maximum velocity is the average of maximum velocities over a cardiac cycle. PI and RI are calculated ratios indicating peripheral resistance. PI is defined as (peak systolic velocity - minimum diastolic velocity)/mean velocity, and RI as (peak systolic velocity - end-diastolic velocity)/peak systolic velocity. The clearest waveform was selected for analysis.

UA doppler USG

Bilateral UA measurements were obtained using abdominal Doppler ultrasound (Voluson E8, GE Healthcare, Salzburg, Austria) at the point where the UA crosses the external iliac artery [32]. With the pregnant woman supine, the UA was identified with color Doppler by slightly tilting the sagittal probe at the level of the internal cervical os, and a regular flow waveform was generated using pulsed wave Doppler.

MCA doppler USG

Optimal MCA waveforms were obtained by visualizing the circle of Willis and the proximal MCA in color flow mapping, just caudal to the transthalamic plane. The probe was positioned on the proximal third of the MCA, near its origin from the internal carotid artery, maintaining an insonation angle close to 0° [32]. Doppler indices were calculated from three consecutive waveforms. MCA Doppler is a routine obstetric assessment for pregnancy complications.

UmA doppler USG

UmA waveforms were obtained from either artery in the cord using color flow and pulsed Doppler, with a probe angle of less than 60°. Measurements were taken from a free segment of the umbilical vessels without compression [32].

UA, MCA, and UmA PI were measured in all participants by a single certified operator (O.Y.) following the guidelines of the Fetal Medicine Foundation and the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) [33, 34].

Intervention

Participants randomized to the exercise group commenced an individualized PFMT home program from the 20th week of pregnancy until delivery. This tailored program was developed for each participant based on digital palpation and PERFECT assessment findings, adhering to training principles outlined by Mørkved et al. [35] and Bø et al. [36].

Initially, participants in the exercise group received comprehensive education on the definition, location, and functions of the PFM, along with instruction on proper contraction technique using anatomical aids. They were instructed to fully relax upon the cue “relax” and to “contract” by squeezing and drawing the PFM inward and upward while maintaining breath and avoiding engagement of abdominal, hip, and thigh muscles. Digital palpation was used to guide participants in correctly contracting their PFM, preventing straining or co-contraction of other muscle groups. Participants were asked to squeeze and lift around the physiotherapist’s fingers, mimicking the sensation of retaining urine or feces [32], to confirm correct activation. Following confirmation of proper technique, an individualized PFMT program was designed and explained based on the PERFECT assessment results, addressing coordination, endurance, strength, and reflex function. Exercises were prescribed in supine, sitting, and standing positions, with participants instructed to perform at least three sets daily, with repetitions tailored to their individual assessment. They were directed to continue the prescribed exercises consistently until their next evaluation. The PFMT program was progressed based on the PERFECT assessment results at subsequent appointments.

An exercise tracking chart was provided to monitor adherence to the home program, with participants asked to record their daily exercise. Separate WhatsApp groups were established for the exercise and control groups. The exercise group received reminders to encourage regular exercise, while the control group received routine pregnancy information. Pregnant women in the control group continued with their standard pregnancy care.

Statistical analysis

Statistical analyses were conducted using IBM SPSS v.26 by a biostatistician blinded to group allocation. Numerical data were summarized using means and standard deviations or medians and ranges, while categorical data were presented as counts and percentages. Normality of data distribution was assessed via the Shapiro-Wilks test and graphical methods (histograms, QQ plots). Group comparisons were performed using independent t-tests or Mann-Whitney U tests as appropriate. For categorical variables, appropriate chi-square tests were applied, including the Pearson chi-square test, Yates corrected, or Fisher’s exact test, depending on expected cell counts. The primary analysis was conducted according to the intention-to-treat (ITT) principle. To address missing values under the ITT framework, multiple imputation was performed using the mice package in R. Multiple imputation was performed using the mice package, generating m = 20 imputed datasets. Statistical analyses were conducted separately on each completed dataset, and the results were combined using Rubin’s rules. For descriptive purposes, the difference between time points was calculated within each of the 20 imputed datasets. The mean and 95% confidence intervals of these difference scores were estimated accordingly. Following imputation, a Generalized Estimating Equations (GEE) model was used to evaluate the significance of main effects for group, time, and their interaction (group × time). When a significant interaction was detected, within-group changes over time were further assessed using the Friedman test. Where appropriate, post-hoc comparisons provided by the software were interpreted accordingly. The GEE models were implemented using the geepack package in R, and graphical visualizations were created using the ggplot2 package. A two-sided p-value of less than 0.05 was considered statistically significant.

Sample size calculation was performed using G*Power 3.1 software. To detect a medium effect size (0.40) between two independent groups with 95% confidence and 80% power, a minimum of 18 participants per group was required. To account for potential attrition and maintain 80% power, the target enrollment was at least 20 participants in each group.

Results

The study was completed with a total of 47 participants, 23 in the exercise group and 24 in the control group (Of the 220 pregnant women reached for the study, 126 wanted to participate, and 69 pregnant women were excluded from the study due to not meeting the inclusion criteria and other reasons. 55 participants were randomized into two groups (Fig. 1).

Fig. 1.

CONSORT diagram of the study

The physical and sociodemographic characteristics of the women are presented in Table 1. The MCA, UA, UmA, and clitoral artery PI values of all pregnant women participating in the study remained within the normal ranges appropriate for gestational weeks in all assessments.

Table 1.

Demographic characteristics of the participants

Demographic Characteristics mean±SD	Exercise Group N:23	Control Group N:24	p
Age (year)	28.13±5.34	27.45±5.88	0.68*
Height (cm)	160.78±5.93	162.46±5.96	0.34*
Weight (kg)	65.82±12.78	68.41±11.14	0.47*
BMI (kg/m²)	25.53±5.47	25.82±3.32	0.83*
Gestational week (number)
First measurement	21.84±2.69	22.71±1.85	0.30*
Second measurement	29.15±1.34	30.21±2.29	0.09*
Third measurement	36.50±0.92	37.31±0.70	0.06*
Birth type n (%)
Vaginal birth	15 (65.2)	17 (70.8)	0.46**
Cesarean section	8 (34.8)	7 (29.2)

BMI Body mass ındex, n number, SD Standard deviation

^*Independent samples t test

^**Chi-squared test, signifcance was accepted as p < 0.05

No statistically significant difference was found between the groups in the clitoral artery, UmA, MCA, and UA PI measurement values at all three time points (p > 0.05). However, a statistically significant decrease in UmA PI values was observed over time in both groups (p = 0.004). Specifically, the mean change between the first and second measurements was 0.111 (95% CI: 0.089 to 0.123) in the exercise group, compared to 0.106 (95% CI: 0.093 to 0.129) in the control group. Between the first and third measurements, the mean decrease was 0.32 (95% CI: 0.305 to 0.343) in the exercise group and 0.260 (95% CI: 0.231 to 0.290) in the control group (Table 2; Fig. 2).

Table 2.

Comparison of clitoral, UmA, MCA, and UA doppler ultrasound results among groups

	Exercise Group n:28 Mean ± SD	Control Group n:27 Mean ± SD	GEE*
			p† (group)	p† (time)	p* (group*time)
UmA PI
First meas.A	1.25 ± 0.03	1.23 ± 0.06	0.639	0.004	0.573
Second meas.A	1.14 ± 0.03	1.12 ± 0.04
Third meas.B	0.93 ± 0.03	0.97 ± 0.05
MCA PI
First meas.	1.98 ± 0.12	2.06 ± 0.12	0.330	0.287	0.226
Second meas.	2.05 ± 0.08	2.07 ± 0.11
Third meas.	2.07 ± 0.11	1.85 ± 0.10
UA PI
First meas.	1.02 ± 0.05	1.04 ± 0.06	0.958	0.127	0.971
Second meas.	0.96 ± 0.04	0.96 ± 0.06
Third meas.	0.87 ± 0.05	0.89 ± 0.06
Clitorial Arter PI
First meas.	2.88 ± 0.76	−0.86 ± 0.86	0.247	0.570	0.419
Second meas.	2.18 ± 0.75	0.84 ± 0.87
Third meas.	2.79 ± 0.99	0.53 ± 1.14
MCA/UmA PI
First meas.	1.56 ± 0.11	1.69 ± 0.15	0.336	0.075	0.266
Second meas.	1.85 ± 0.09	1.93 ± 0.10
Third meas.	2.27 ± 0.11	2.10 ± 0.07

UmA Umbilical artery, UA Uterine artery, MCA Middle cerebral artery, meas measurement, PI Pulsality ındex

^*Generalized estimating equations (GEE); significance was accepted as p < 0.05, ^*Letters (A, B, etc.) denote the results of post-hoc comparisons. Groups sharing identical letters (e.g., AA) are not significantly different from each other, whereas groups labeled with different letters (e.g., AB) exhibit statistically significant differences (p < 0.05)

Fig. 2.

Changes in the clitoral artery, Umbilical Artery (UmA), Uterine Artery (UA), Middle Cerebral Artery (MCA) Pulsatility Index with gestational age

A statistically significant change over time was not observed in MCA PI and UA PI values (p = 0.287 and p = 0.127, respectively, Table 2; Fig. 2.). Regarding the MCA/UmA PI ratio, although the differences between first and second measurements were − 0.287 (95% CI −0.337 to −0.236) for exercise, and − 0.247 (95% CI −0.321 to −0.173) for control group, and between the first and third measurements − 0.701 (95% CI −0.769 to −0.633) and − 0.410 (95% CI −0.490 to −0.330), respectively, the time was borderline non-significant (p = 0.075) based on the GEE model.

PFM function, as assessed by the PERFECT scheme, revealed significant group-by-time interactions for both endurance and fast contraction components (p = 0.050 and p = 0.033, respectively). Therefore, these parameters were analyzed separately by group and time point. In the exercise group, endurance values showed a significant time-dependent increase (p < 0.001). Notably, the exercise group demonstrated significantly higher endurance values than the control group at all time points (p < 0.005). The mean change between the first and second measurements was 12.1 (95% CI: 11.2 to 13.0) in the exercise group, compared to −3.4 (95% CI: −4.72 to −2.08) in the control group. Between the first and third measurements, the mean decrease was − 23.3 (95% CI: −24.55 to −22.02) in the exercise group and − 6.8 (95% CI: −8.20 to −5.40) in the control group (Table 2; Fig. 2).

For fast contraction values, no significant difference was detected between groups at baseline; however, the exercise group showed significantly greater improvements than the control group at subsequent time points. A significant time effect was observed for both groups in fast PFM measurements (Table 3). The average of differences between first and second measurements were − 9.0 (95% CI −8.29 to −9.71) for exercise, and − 2.23 (95% CI −3.83 to −5.35) for control group, and between the first and third measurements − 14.8 (95% CI −14.12 to −15.46) and − 7.25 (95% CI −6.43 to −8.07), respectively.

Table 3.

Comparison of PFM PERFECT and USG assessment results among groups

	Exercise Group n:23 Mean ± SD	Control Group n:24 Mean ± SD		GEE*
				p† (group)	p† (time)	p* (group*time)
PFM PERFECT
Power PFM
First meas.	2.50 ± 0.22	1.12 ± 0.16		0.219	0.388	0.753
Second meas.	2.55 ± 0.22	1.23 ± 0.18
Third meas.	2.69 ± 0.20	1.49 ± 1.19
Endurance PFM
First meas.	9.15 ± 1.79A	6.00 ± 1.81	0.001
Second meas.	21.30 ± 2.16B	9.40 ± 2.22	0.003	0.805	0.038	0.050
Third meas.	31.9 ± 2.60B	12.80 ± 2.63	0.008
	< 0.001	0.052
Fast PFM
First meas.	10.0 ± 1.20A	5.95 ± 1.07A	0.082	0.904	0.014	0.033
Second meas.	18.5 ± 1.01B	8.18 ± 1.72AB	< 0.001
Third meas.	24.3 ± 1.62B	13.2 ± 1.37B	< 0.001
	< 0.001	0.010
PFM USG
ML relax.(cm2)
First meas.	3.45 ± 0.08	3.26 ± 0.01		0.783	0.633	0.719
Second meas.	3.24 ± 0.11	3.31 ± 0.01
Third meas.	3.37 ± 0.12	3.46 ± 0.02
SI relax.(cm2)
First meas.	4.66 ± 0.09	4.82 ± 0.16		0.713	0.189	0.644
Second meas.	5.00 ± 0.12	4.59 ± 0.15
Third meas.	4.28 ± 0.13	4.32 ± 0.20
SI kont. (cm2)
First meas.	4.71 ± 0.10	4.32 ± 0.23		0.340	0.430	0.301
Second meas.	3.79 ± 0.15	3.95 ± 0.11
Third meas.	3.77 ± 0.16	3.88 ± 0.19
LHA kont.(cm2)
First meas.	8.93 ± 0.30	9.13 ± 0.69		0.970	0.499	0.553
Second meas.	8.49 ± 0.45	10.23 ± 0.34
Third meas.	8.84 ± 0.51	9.73 ± 0.57

Groups sharing identical letters (e.g., AA) are not significantly different from each other, whereas groups labeled with different letters (e.g., AB) exhibit statistically significant differences (p < 0.05)

meas: USG Ultrasoundography, measurement, relax, relaxation, kont kontraxion, LHA Levator hiatal area, S-I Superior-Inferior, M-L Medio-Lateral

^*Generalized estimating equations (GEE); significance was accepted as p < 0.05, ^*Letters (A, B, etc.) denote the results of post-hoc comparisons

USG assessments showed no significant differences in any parameters across time points (Table 3; Fig. 3).

Fig. 3.

Changes in PFM Function with Gestational Age

Adverse events and safety

During the study, no undesirable events, side effects, or adverse outcomes were observed in pregnant women who underwent PFMT. No serious adverse events were reported by participants or detected by researchers.

Discussion

This study aimed to evaluate the effects of PFMT on clitoral artery, UmA, MCA, UA blood flow parameters and PFM function in pregnant women. The results of this study revealed that PFMT applied during pregnancy has clinically significant effects on PFM function, and suggests potential beneficial adaptations in maternal and fetal circulatory systems.

While the clitoral artery, UmA, MCA, and UA PI values did not show a statistically significant difference between the groups, the marked decreasing trend observed in UmA PI values in the exercise group suggests that PFMT may be effective in reducing vascular resistance. The statistically significant increase observed in PFM endurance, fast twitch values in the exercise group indicates that PFMT is effective in increasing PFM strength during pregnancy, and this effect is more pronounced compared to the control group. These findings collectively support that PFMT may have positive effects on both maternal pelvic floor health and fetal well-being during pregnancy and that recommending PFMT to pregnant women in clinical practice may be beneficial.

Pregnancy leads to major cardiovascular changes, including reduced systemic vascular resistance and increased cardiac output, which are vital for proper uteroplacental blood flow and fetal development [37]. The effect of exercise on this blood flow depends on the exercise type and intensity. High-intensity exercise can cause a temporary drop in blood flow, while the effects of low- to moderate-intensity exercise are less clear [38], with varying study results [39–41]. Some studies suggest that moderate-intensity exercise throughout pregnancy can improve UA, MCA, and UmA blood flow parameters as pregnancy progresses [16, 42]. However, there is limited research on the specific effects of PFMT on UA blood flow. One study found that a 16-week PFMT program significantly reduced the UA PI at 36 weeks of gestation [12]. Our current study, however, did not find a statistically significant difference in UA PI values between the exercise and control groups. Despite this, other positive effects of PFMT, such as improvements in PFM function, suggest it is a safe and beneficial exercise during pregnancy. Definitive conclusions about its effect on UA blood flow require larger studies.

Lifestyle and exercise are key to fetal well-being [43, 44]. While organizations like American College of Obstetricians and Gynecologists (ACOG) recommend exercise for pregnant women [43], more research is needed on its effects on placental gas and nutrient exchange. MCA blood flow is vital for fetal brain development [25]. Studies on core exercises showed a significant decrease in MCA PI and RI [45]. However, a study on PFMT found no significant changes in MCA blood flow, possibly due to the low intensity and small muscle mass involved [12]. Existing literature generally shows that MCA PI tends to decrease as pregnancy progresses. In cases of intrauterine growth restriction, rapid changes in these parameters are considered negative indicators [46]. Our study found no significant difference in MCA PI or UA PI between the exercise and control groups, although there was a slight decreasing trend in UA PI in the exercise group. This suggests PFMT might have some influence on blood flow, but more research is needed. Other studies show that exercise intensity is crucial for UmA and UA blood flow. For example, a decrease in UmA S/D ratio post-exercise has been linked to increased placental circulation [47], while very high-intensity exercise may lead to high UmA PI values [48].

The MCA/UmA ratio is an important measure in fetal Doppler ultrasound, showing the balance of blood flow between the brain and the placenta. A ratio above 1 is often seen as a sign of the fetus adapting to a lack of oxygen or nutrients by increasing blood flow to the brain [49]. Our study found no significant difference in this ratio between the exercise and control groups. While we observed a small, non-significant increase in the ratio within the PFMT group, we cannot conclude that PFMT helps protect the fetal brain based on this finding. To fully understand the long-term effects of PFMT on fetal brain development and its impact on the MCA/UmA PI ratio, future studies with larger groups and follow-up after birth are needed.

General research shows that moderate exercise during pregnancy is safe and doesn’t increase risks like fetal hypoxia or affect growth [23, 42, 50, 51]. However, research on the long-term effects of PFMT specifically is limited [12], and studies on how chronic exercise affects uteroplacental and fetal Doppler parameters are rare and have mixed results [42, 52]. It’s widely accepted that regular, supervised moderate exercise in low-risk pregnancies doesn’t harm fetal or maternal Doppler parameters [16, 23]. This is because while exercise initially might shift blood flow away from the placenta, the mother’s cardiovascular system adapts, ultimately improving placental perfusion and oxygenation. The UmA PI is a key indicator of this process [53]. Our findings suggest that a well-designed PFMT program, like other forms of exercise, may also contribute to this beneficial physiological adaptation. By strengthening the pelvic floor muscles, PFMT could positively influence blood flow in the pelvic region, leading to improved placental perfusion. More research is needed to fully understand the unique effects of PFMT, but our results support the idea that it can be a safe and beneficial part of a comprehensive pregnancy exercise routine.

During pregnancy, neoangiogenesis and vasodilation of the uterine and other pelvic arteries are vital for redirecting blood flow to the developing fetus and uterus [54, 55]. This process, driven by hormonal changes, increases blood volume in the clitoris and labia minora, which can positively impact sexual function [56, 57]. Despite the known link between pelvic floor muscle activity and vulvovaginal blood flow, our study did not find a significant change in PI values in either group. This suggests more research is needed to understand the full effects of personalized PFMT on pelvic blood flow during pregnancy. From a clinical perspective, incorporating individualized PFMT into prenatal care may offer benefits for women’s sexual health by potentially improving vulvovaginal blood flow and preventing postpartum issues. This could significantly improve a woman’s overall quality of life during and after pregnancy.

Exercise can cause temporary changes in uteroplacental and fetal blood flow, but this doesn’t mean the fetus is in distress. These changes are normal adaptations to meet the mother’s needs. In healthy pregnancies, the fetus has effective compensatory mechanisms that prevent hypoxia [58]. Our study suggests that a personalized PFMT program is a safe and effective way to promote healthy physiological adaptations, like stronger pelvic floor muscles and improved umbilical blood flow. While we didn’t find significant changes in the UA, MCA, or clitoral artery blood flows, our results still point to the potential benefits of PFMT for maternal and fetal health.

This study has some limitations. The study was conducted at one center with a small number of participants. This limits how widely the findings can be applied to other populations. Future research should include more centers and a larger sample size. We depended on participants to report their own exercise habits. This can be inaccurate due to self-reporting bias. In the future, objective methods like wearable devices or verified exercise logs should be used to get a more accurate measure of adherence. We didn’t follow up with the infants after they were born to assess their neurodevelopment. Because of this, we can’t confirm any long-term benefits of PFMT on fetal brain development. This is a critical area for future research.

Our study suggests that personalized PFMT during pregnancy can improve both maternal pelvic floor strength and blood flow in the fetal and fetal-maternal circulatory systems. The observed increase in fetal umbilical artery (UmA) blood flow indicates that PFMT may benefit fetal well-being and neurodevelopment. However, we did not find significant changes in MCA, UA, or clitoral artery blood flow. Further research is needed to explore the mechanisms behind PFMT’s effects on fetal circulation, evaluate long-term outcomes, and compare different PFMT protocols.

Clinical message

• Individualized PFMT during pregnancy demonstrates positive effects on PFM function, specifically improving endurance and fast twitch muscle fibers. These improvements can contribute to better pelvic floor health in pregnant women.

• While no statistically significant differences were observed in the PI of the clitoral, UmA, MCA, and UA arteries between the PFMT and control groups, the more pronounced decrease in UmA PI in the PFMT group suggests a potential for improved fetoplacental perfusion as pregnancy progresses.

• Considering the positive impacts of PFMT on both maternal pelvic floor health and indicators of fetal well-being, including potentially improved fetoplacental perfusion, recommending individualized PFMT programs to pregnant women in clinical practice may be beneficial.

Abbreviations

MCA

Middle cerebral artery

UA

Uterine artery

UmA

Umbilical artery

PI

Pulsatility index

RI

Resistance index

PFM

Pelvic floor muscle

PFMT

Pelvic floor muscle training

USG

Ultrasonography

LHA

Levator hiatal area

Authors’ contributions

MBS: Data collection, Manuscript writing, Project development. MBG: Statistical analysis. GT: Data collection. SÇG: Data collection, Manuscript writing. SK: Data Collection. OÇT: Project development, Manuscript writing. OY: Data Collection.

Funding

The authors did not receive support from any organization for the submitted work.

Data availability

The datasets used in this study are available from the corresponding author upon reasonable request. These datasets will be provided in an anonymized and/or de-identified format to protect participant confidentiality.

Declarations

Ethics approval and consent to participate

This study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by Dokuz Eylul University the Institutional Non-invasive Research Ethics Board on 27.11.2024 (Number: 2024/43-27-GOA).

Consent for publication

All participants provided consent for publication of any identifying information or data included in this manuscript.

Competing interests

The authors declare no competing interests.