Updated: Jan 27
This post is inspired by a topic near and dear to me: the somewhat unique considerations that an athlete might consider when preparing for childbirth. When I was pregnant with my first child, I pushed my athleticism pretty hard (you can read more about my experience here). I was aware of a common-sense list of reasons to cease or avoid exercise during pregnancy (which contained things like vaginal bleeding, shortness of breath before beginning activity, and dizziness) and I never experienced anything worrisome. When it came time to deliver my daughter, I accomplished a challenging and somewhat traumatic (physically and mentally) vaginal birth. My labor was long and extremely painful, I had a significant tear and I developed a bladder prolapse. The pelvic floor dysfunction that is a legacy of that pregnancy and childbirth will always leave me wondering how much was due to my athletic choices during pregnancy, my physical tendencies, the specific circumstances of my delivery and/or the interplay between all of these factors.
In the United States, the gold standard in pregnancy exercise recommendations comes from the American College of Obstetricians and Gynecologists (ACOG). In April 2020, ACOG updated their guidelines and continue to recommend that pregnant women engage in aerobic and “strength-conditioning” exercises for at least 150 minutes per week . The recommendations consider numerous positive outcomes of prenatal exercise including a reduction in risk of gestational diabetes, a reduced risk of instrument-assisted or cesarean birth and reduced incidence of postpartum depression.
For the first time, the 2020 ACOG guidelines contain a special section labeled “Athletes” under the header “Special Populations“. The guidelines only consider high-level athletic activity as it impacts fetal health. Not surprisingly, “pelvic floor” is only mentioned once anywhere in the guidelines, and it is with respect to postpartum rehabilitative exercises. In a recent review, pelvic floor researchers Kari Bo and Ingrid Nygaard  state, “The pelvic floor may be the only area of the body where the positive effect of physical activity has been questioned.” Given the extremely high prevalence of pelvic floor dysfunction that develops in pregnant and postpartum people, I find ACOG’s oversight extremely disappointing. When it comes to pelvic floor health during pregnancy, knowledge is essential to evaluating the risks versus rewards of our recreational pursuits.
But back to my musings: Could my athletics have negatively impacted my pelvic floor and my birth experience? As I considered my own experience, I became curious and started to dig a little bit into the research. I specifically looked for any definitive information about how, on average, athletic performance during pregnancy impacts labor and delivery outcomes, specifically with respect to prolonged labor and pelvic floor injuries. Pregnancy is, independent of childbirth, a risk factor for long-term pelvic floor dysfunction. There are ways to manage athleticism during pregnancy to mitigate that risk, although that discussion is outside the scope of this post.
Before we dig too deep, let’s talk about who is an athlete and why they might have a more challenging delivery. First, who is an “athlete”? An “athlete” is anyone regularly pursuing fitness, exercise or movement. Athleticism spans a spectrum of intensity and the way in which your athleticism impacts your pregnancy probably depends on your choice of activity, the intensity at which you pursue it and will vary a lot from person to person. There’s a lot of room for interpretation in this term, and as we’ll see, it makes it really hard to extrapolate from the academic literature.
So, now the “why”: Why might athletes have more challenging labor and delivery experiences? One hypothesis is that reflexive contraction of the pelvic floor muscles during sport effectively strengthens these muscles along with the rest of the skeletal muscles . Depending on the athlete, they might have higher tone or muscle mass in their pelvic floor and the size of the levator hiatus (basically, the hole in the deep pelvic floor muscles that the baby needs to pass through) might be smaller as a result [4, 5]. You might imagine that a tighter or more-toned pelvic floor, with a smaller opening (that can not relax or yield) might lead to a longer second stage (i.e. pushing stage) and more physical trauma to the perineum. In fact, several studies implicate a prolonged second stage with the incidence of severe tearing, pelvic organ prolapse and incontinence (for example, [6-8]). These conditions, while perhaps secondary to concerns about maternal and fetal mortality, are outcomes with a significant bearing on the long-term health and well-being of the birthing parent.
Several academic papers suggest that physical activity or athletics might lead to changes in the pelvic floor which result in more challenging labor and delivery experiences [4, 9-12]. In one study, researchers interviewed nine obstetric caregivers and recorded their experiences and perceptions attending to pregnant athletes in labor . The caregivers represented a range of obstetric specialties, had practiced for at least ten years, worked with a variety of pregnant people and attended births of “highly trained athletes”. Although anecdotal, the overwhelming perception of providers interviewed is that highly trained athletes had, on average, more challenging labors characterized by prolonged second stage. In several studies, Jennifer Kruger and colleagues have gone on to measure anatomical changes in pelvic floor muscles resulting from intense exercise and have suggested that these changes may lead to unexpected difficulties during labor (for example [4, 11]).
Two studies have directly tested this idea. Marco Parente and co-workers computationally modeled the amount of force generated by the fetal head during delivery through pelvic floor muscles engaged at various levels of contraction . Their results suggest pelvic floor activation (perhaps a proxy for high-tone or non-relaxing muscles) represented an obstacle to descent of the fetus through the birth canal and resulted in higher values of stress on the (simulated) pelvic floor. They suggest this increase in stress could lead to pelvic floor injury. Xinhsan Li and co-workers used computational modeling to investigate the impact of muscle hypertrophy (muscle growth resulting from exercise) on the pelvic floor dynamics of athletes and non-athletes during labor and delivery . They determined that 45% greater force was required to delivery the fetal head through the pelvic floor of the athlete as compared to the non-athlete model. Since increased strain on the pelvic floor is correlated with pelvic floor damage, the implication is that if more force is required to deliver a baby through a more muscular pelvic floor, the pelvic floor will be at greater risk for damage. It is worth noting that the two papers that draw conclusions in this regard are based on modeling output rather than data on actual people. These types of studies are incredibly difficult to perform in real-time on real birthing people and for the time being, modeling studies provide some interesting and hard-to-achieve insights.
In contrast, there are several studies that conclude that people who exercise do not have more difficult deliveries (with respect to length of second stage, emergency c-section rate, perineal tearing) [5, 13-15]. In fact, the same conclusion was reached by a 2016 International Olympic Committee expert group on exercise and pregnancy in recreational and elite athletes which considered labor outcomes with respect to unplanned cesarean births, prolonged labor, risk of pelvic floor injury and risk of anal sphincter tear, among others . Consistent with the abovementioned studies, they concluded that physical activity during pregnancy has no effect on the length of the second stage (pushing stage) of labor and that regular exercise may somewhat decrease the risk of emergency cesarean birth. However, they found insufficient data to draw conclusions about the risk of anal sphincter tears or pelvic floor injury (the piece I’m really curious about!).
One of the challenges I faced in considering the studies references above, is that they all study very different populations of athletes. Some of these studies focus on “elite” athletes . Others bin people into “exercise” vs. “non-exercise” groups with little insight into what types of exercise are performed . In some cases, exercise is carefully controlled and supervised by a physiotherapist . In the latter case, it is likely very “safe” prenatal exercise rather than the activities many pregnant athletes may be engaging in. In another study, the type of exercise is described as “light resistance and toning exercise” and may not be directly applicable to athletes working at higher intensity.
While clearly there is a difference between “non-exerciser” and “elite athlete”, my hunch is there is also likely a difference between recreational athletes performing low-intensity, physiotherapist-supervised strength training and someone working out 5-days a week in a CrossFit box. I would also not be surprised to learn that a career athlete, who’s training is carefully planned and overseen by professional coaches, manages the stress of exercise on their body in a different way than an everyday exerciser working at a reasonably high level of intensity. In reading these studies, I did not find myself, a mid-distance runner and hard-style kettlebell junkie, represented in the studies.
While studies such as those described above provide food for thought and preliminary data, they do not (and can not) paint a comprehensive picture of the unique demands any particular sport places on an individual pregnant athlete or their delivery outcomes. Ultimately, there are very few studies of the effect of strength training and high-impact exercise on childbirth outcomes, specifically with respect to the long-term health of the pelvic floor. Of the studies that do exist, some consider only a very small number of pregnant athletes or exercises, many rely on self-reported data and the types and intensity of exercise performed by participants varies wildly.
In their recent review, Kari Bo and Ingrid Nygaard  conclude that exercising women do not have a greater risk of obstructed labor or childbirth. But, they also acknowledge that management of intra-abdominal pressure (and subsequent impact on pelvic floor) varies significantly between individuals and activities. They also acknowledge that the threshold for various outcomes varies person to person. This is key: there is still a lot we still don’t know.
The data are clear, that by many metrics, exercise is beneficial to the pregnant person [1, 17]. However, the data are not definitive when it comes to the health and function of the pelvic floor. While many athletes will have no delivery complications, it is up to the individual to evaluate their individual risk factors and prepare for childbirth accordingly. If you want professional guidance assessing your pelvic floor and determining your unique considerations, a pelvic health physical therapist is the most appropriate clinician to assist you. Most obstetric providers have no specialized training in assessment or management of the pelvic floor.
As a birth professional and specialist in prenatal exercise, should I be offering advice to athletes regarding the way in which they prepare for labor and delivery? Certainly I hear anecdotal stories from fellow doulas, pelvic floor physical therapists and midwives that they see their athlete clients and patients experience more challenging labors. But can we trust anecdotes? Anecdotes aren’t backed by science and inevitably recall of such labors is biased by personal experience and perspective. Yet, with respect to a question that has not been sufficiently researched, it may be worth considering the clinical experiences and opinions of clinicians and other professionals who have spent their careers caring for a wide spectrum of pregnant people (e.g. ). Ultimately, I do advise my clients to consider preparing their bodies and their pelvic floor for labor. I offer generally applicable tools and strategies; I leave specifics to the physical therapists. One of my missions as a perinatal fitness professional and birth doula is to help people identify ways to preserve their long-term pelvic health; this is a way to do it. There is no harm in erring on the side of caution.
When I became pregnant with my second child, I chose to confront my exercise and birth preparation very differently than I did during my first pregnancy. I didn’t need to wait for a study to tell me there might be benefit in taking steps to down-train my pelvic floor for in preparation for labor. Ultimately, the labor outcome was much more positive emotionally and physically. I’ll never know if the changes I made to my preparation are responsible. And honestly, I’m not sure that it really matters. I am not here to tell you that you should be preparing for your birth in the same manner in which I prepared for mine. Every pregnancy and every labor are unique and come down to many factors outside of our control. But I chose to control what I could and at a minimum, I felt more empowered and more satisfied by the course of my delivery.
I can’t tell you what to do. I can’t tell you that you need to prepare for your birth in any special way or that you don’t. I’m sharing information that I hope helps you begin to think about how you manage your prenatal fitness and athletics and how you approach your birth preparation. I encourage you to seek care or consultation with a pelvic floor physical therapist, preferably one with experience managing athletes engaged in the same sports as you. I also encourage you to work towards developing pelvic floor awareness and learning to down-train (relax) your pelvic floor in preparation for labor. If you would like to learn more about specific strategies you can use to accomplish these goals, stay tuned for The Athlete’s Guide to Childbirth Preparation. You can get on the waitlist here (to be released in late July 2020). It’s packed with tools and strategies to help you prepare for an efficient labor and delivery. Will it guarantee your ideal birth? Nothing will. But perhaps you can stack the deck in your favor.
1. Obstetricians, A.C.o., Gynecologists, and C.o.O. Practice, Physical activity and exercise during pregnancy and the postpartum period. Obstet Gynecol, 2020. 135(4): p. e178-188.
2. Bø, K. and I.E. Nygaard, Is Physical Activity Good or Bad for the Female Pelvic Floor? A Narrative Review. Sports Medicine, 2020(50): p. 471-484.
3. Bø, K., Urinary incontinence, pelvic floor dysfunction, exercise and sport. Sports medicine, 2004. 34(7): p. 451-464.
4. Kruger, J.A., B.A. Murphy, and S.W. Heap, Alterations in levator ani morphology in elite nulliparous athletes: a pilot study. Australian and New Zealand journal of obstetrics and gynaecology, 2005. 45(1): p. 42-47.
5. Bø, K., et al., Does general exercise training before and during pregnancy influence the pelvic floor “opening” and delivery outcome? A 3D/4D ultrasound study following nulliparous pregnant women from mid-pregnancy to childbirth. British journal of sports medicine, 2015. 49(3): p. 196-199.
6. Dietz, H.P. and M. Bennett, The effect of childbirth on pelvic organ mobility. Obstetrics & Gynecology, 2003. 102(2): p. 223-228.
7. Turner, C.E., et al., Incidence and etiology of pelvic floor dysfunction and mode of delivery: an overview. Diseases of the Colon & Rectum, 2009. 52(6): p. 1186-1195.
8. de Leeuw, J.W., et al., Risk factors for third degree perineal ruptures during delivery. BJOG: An International Journal of Obstetrics & Gynaecology, 2001. 108(4): p. 383-387.
9. Li, X., et al. Modelling childbirth: comparing athlete and non-athlete pelvic floor mechanics. in International Conference on Medical Image Computing and Computer-Assisted Intervention. 2008. Springer.
10. Parente, M.P., et al., The influence of pelvic muscle activation during vaginal delivery. Obstetrics & Gynecology, 2010. 115(4): p. 804-808.
11. Kruger, J., H. Dietz, and B. Murphy, Pelvic floor function in elite nulliparous athletes. Ultrasound in obstetrics & gynecology, 2007. 30(1): p. 81-85.
12. Kruger, J., B. Murphy, and S. Thompson, Childbirth and sportswomen: the perceptions of obstetric caregivers. Vision, 2006. 14(2): p. 7-15.
13. Sigurdardottir, T., et al., Do female elite athletes experience more complicated childbirth than non-athletes? A case–control study. Br J Sports Med, 2019. 53(6): p. 354-358.
14. Salvesen, K.Å., et al., Does regular exercise in pregnancy influence duration of labor? A secondary analysis of a randomized controlled trial. Acta obstetricia et gynecologica Scandinavica, 2014. 93(1): p. 73-79.
15. Barakat, R., et al., Type of delivery is not affected by light resistance and toning exercise training during pregnancy: a randomized controlled trial. American journal of obstetrics and gynecology, 2009. 201(6): p. 590. e1-590. e6.
16. Bø, K., et al., Exercise and pregnancy in recreational and elite athletes: 2016 evidence summary from the IOC expert group meeting, Lausanne. Part 2—the effect of exercise on the fetus, labour and birth. British journal of sports medicine, 2016. 50(21): p. 1297-1305.
17. Clapp III, J.F. and C. Cram, Exercising through your pregnancy. 2012: Addicus Books.
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Contact me if you have questions about exercise or pelvic health pertaining to pregnancy or postpartum. I work with people locally (Seattle's Eastside: Redmond, Bellevue, Kirkland and surrounding areas) and online to develop personalized pregnancy and postpartum personal training plans. I also offer labor support (doula services) within the greater Seattle-Metro Area.