As a Women’s Health physio, this question has occurred to me. And I have been asked by women too. They may have been told that having a tight pelvic floor may be the reason they had a more challenging birth. But can having strong or ‘tight’ pelvic floor muscles really cause a problem in labour? Some research has been done to explore this and these are some of the questions that have come up:

1. How do we even measure a tight pelvic floor?
2. Do women who exercise have tighter pelvic floor muscles?
And of course:
3. Does having tight pelvic floor muscles affect birth outcomes at all?

Measuring the Pelvic Floor

Let’s look at question 1 first. Researchers have looked at several different ways of measuring the tightness of the pelvic floor muscles. The methods most commonly used are manometry (where pressure in the vaginal canal is measured using a squeeze bulb connected to a computer). And ultrasound, often 3D and 4D which can assess the size of the levator hiatus (the gap in the pelvic floor muscles that the baby needs to pass through). It’s unclear from the research whether the size of the levator hiatus is connected with the amount of tightness in the pelvic floor muscles. There is however, some correlation between vaginal resting pressure (measured by manometry) and pelvic floor tightness as assessed by a specialist physiotherapist.

What Causes Tight Pelvic Floor Muscles?

Several factors have been associated with tight pelvic floor muscles. These include psychological factors such as anxiety or past traumas, recurrent UTIs (urinary tract infections), low back or pelvic pain, high levels of exercise and more. In lots of these cases, we’re often not sure whether the association is the cause or the result of the pelvic floor tightness. There also hasn’t been a lot of research to explore the various factors that might cause pelvic floor overactivity.

One factor that has been looked at however, is high activity levels. In the past it was thought that women who were very active before and/or during pregnancy may have tighter pelvic floor muscles. It was suggested that this might lead to more complications for active women during their births.

When they looked at this hypothesis, researchers actually found that not only did women who exercised during pregnancy NOT have tighter pelvic floors, but that being active during pregnancy might contribute to:

• Shorter first stage of labour
• Decreased risk of instrumental birth (forceps and vacuum)
• Decreased risk of both emergency and elective caesarean birth

Do Tight Pelvic Floor Muscles Cause Problems in Labour?

Kari Bø and her research team looked at outcomes for a large group of women and compared their vaginal pressure readings. They found that women who had longer second (pushing) stage tended to have higher resting vaginal pressures at around 20 weeks of pregnancy. This suggests that tight pelvic floor muscles MAY lead to a slightly longer pushing stage of labour. When it comes to perineal tearing and assisted births (forceps or vacuum), Bø concludes that ‘strong pelvic floor muscles are not disadvantageous for vaginal delivery’.

Other studies looked at whether performing pelvic floor exercises changed birth outcomes. What they found might surprise you!

One study found that doing pelvic floor exercises didn’t affect labour and birth outcomes. Two others found that doing pelvic floor exercises actually might contribute to a SHORTER pushing stage of labour. Another suggested the pelvic floor muscle training during pregnancy ‘may improve muscle control and both strengthen the muscles and enhance the ability to relax, which might influence the process of labour positively’.

This research doesn’t really change what we, as physiotherapists advise women under our care in pregnancy. These recommendations include:

• Regular exercise.
• Pelvic floor exercises (twice or three times a day).
• Make sure you’re confident that you’re performing your pelvic floor exercises correctly (if not, see your women’s health physio for a one to one appointment).
• Write birth preferences.

Patience is a Virtue

Lastly, it’s important to remember that women’s bodies are designed to give birth. Most often it is factors outside of our bodies that determine birth outcomes, particularly in a hospital setting. For example, time limits on the second stage of labour, not being able to move around in labour, coached pushing and the CTG are all more likely increase your risk of instrumental birth, perineal tears and emergency caesarean than having tight pelvic floor muscles. If labour is slow, but all is well with you and your baby, patience is usually the key.

Find a Women’s Health Physio in Ireland:

Irish Society of Chartered Physiotherapists

Useful articles

Tips to Avoid an Instrumental Birth

Top Tips During Pregnancy for Reducing Your Risk of Perineal Tears

 

References

Bø, K., Hilde, G., Jensen, J.S. et al. Int Urogynecol J (2013) Too Tight To Give Birth? 24: 2065.

Salvesen KA, Mørkved S (2004) Randomised controlled trial of pelvic floor muscle training during pregnancy. BMJ 329:378–380

Bø, Kari, Caroline Fleten, and Wenche Nystad. “Effect of antenatal pelvic floor muscle training on labor and birth.” Obstetrics & Gynecology 113.6 (2009): 1279-1284.

Agur, Wael, et al. “Does antenatal pelvic floor muscle training affect the outcome of labour? A randomised controlled trial.” International Urogynecology Journal 19.1 (2008): 85-88.

Van Veelen, G. A., et al. “Association between levator hiatal dimensions on ultrasound during first pregnancy and mode of delivery.” Ultrasound in Obstetrics & Gynecology 45.3 (2015): 333-338.

Dias, L. A., Driusso, P., Aita, D. L., Quintana, S. M., Bø, K., & Ferreira, C. H. (2011). Effect of pelvic floor muscle training on labour and newborn outcomes: a randomized controlled trial. Brazilian Journal of Physical Therapy, 15(6), 487-493.

Du, Yihui, et al. “The effect of antenatal pelvic floor muscle training on labor and delivery outcomes: a systematic review with meta-analysis.” International urogynecology journal 26.10 (2015): 1415-1427.

Bø, Kari, 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.” Br J Sports Med 49.3 (2015): 196-199.

Pool-Goudzwaard, A.L., Slieker ten Hove, M.C.P.H., Vierhout, M.E. et al. Relations between pregnancy-related low back pain, pelvic floor activity and pelvic floor dysfunction. Int Urogynecol J (2005) 16: 468.

 

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