Okay, okay, I was wrong! It happens. Sometimes the brain gets in the way of scientific studies –prejudges them. Alters them in little ways so they do not conflict with its own opinions. Or, worse still, is influenced by a confirmation bias that precludes even the perusal of any information that makes it uncomfortable. The brain can be its own editor, redacting reams of otherwise useful knowledge, recusing itself inappropriately. None of us readily admit guilt in this respect, of course. In a sense, we are blind to it… or want to be.
I’m a gynaecologist as well as an obstetrician, so I have long been aware of the value of strengthening the pelvic floor muscles to prevent urinary incontinence amongst other things. There are a set of muscles –the levator ani muscles- that act as a kind of pelvic platform and help support the various organs that transit through the area, notably the bladder, uterus, and rectum. Exercising them was proposed by a Dr. Kegel in 1952, albeit to strengthen their ability to narrow the vagina and hence the ease of orgasm. I think a more frequently admitted use, is to reduce urinary incontinence, however. Indeed, to discover the correct muscle for training, the woman need only attempt to stop her urinary stream and she has identified the correct one.
Prominent among the levator ani muscles is the pubococcygeus muscle. (The name merely describes where the muscle starts –the pubic bone, and where it ends- the coccyx, or tail-bone. On its journey, it wraps around, first the urethra –the tube that empties the bladder- and then the vagina, and finally the rectum, like a series of hammocks). The fact that strengthening it can constrict the vaginal diameter when contracted, has always been a kind of two-edged sword for those of us who deliver babies. On the one hand, there is some fairly longstanding and convincing evidence that it can indeed help to prevent the involuntary loss of urine (urinary incontinence). But remember that it not only helps support the bladder and its opening, it is also a hammock that supports and constricts the vaginal canal. Well, that’s what the baby has to squeeze through… So, does the one benefit become a detriment to the other? Are you robbing Petra to pay Paula?
I have to admit that I was one of the exercise skeptics; it made sense to me that the stronger the muscles that surround the vagina -the greater their bulk- the narrower and more difficult the passageway for the baby to pass through at delivery. At the very least, I reasoned, it would take a greater effort on the part of the mother to force her baby through. And all this at a time when she is already exhausted from her labour. Maybe it would make more sense to work on strengthening those muscles in the weeks and months after delivery. Everything in the area was stretched or torn from the effort of actually pushing the baby’s head out, so perhaps the benefits would accrue if those muscles were strengthen then –a sort of postpartum rehabilitation.
In other words, would strong pelvic floor muscles increase complications in either labour or birth? Would there be a higher incidence of Caesarian Sections, for example? Or the need for episiotomy (cutting the skin at the opening of the vagina) to allow more room for the baby’s head to descend? Would there be a greater need for so-called operative delivery (forceps or vacuum extraction)?
Well, here’s where the information from large studies are more helpful than personal experience. Each of us carries a bias –acknowledged, or buried deep within our own reminiscences of similar situations. If I, for example, believe that the Kegel exercises are a hindrance to normal delivery, I am more likely to remember any episodes in my career where that might indeed have played a role –unaware, or maybe conveniently forgetting (or not even asking about) times when it didn’t. Confirmation bias again. Limited, or selective, observations are not necessarily a valid reflection of the collective reality. They amount to opinions, not proof, and carry only as much weight as the prestige of the propounder allows. In my case, it was never very much…
The benefit of Kegel exercises in pregnancy remained somewhat controversial in the obstetrical community –at least amongst us iconoclasts- until some Norwegian researchers, notably Kari Bo at the Norwegian School of Sport Sciences, decided to investigate it in a large group of women (18,865 primiparous women) who practiced Kegel exercises at various frequencies per week during pregnancy. The group then looked at the outcome and complications of their labours and deliveries. http://www.ncbi.nlm.gov/pubmed/19461423 There was no difference in outcomes between those who did Kegels religiously in pregnancy, and those who did not. Presumably, the pelvic floor muscles –as strong (and bulky?) as they had become- were able to relax enough to allow normal passage of the baby.
I learned a lot from that paper –and a lot about the way my beliefs interpret my experience. A lot, too, about the way many of us travel through our lives, influenced as we are by only limited familiarity or exposure to events, and drawing perhaps unwarranted –or at least unproven- conclusions from them. And although it is inductive reasoning with all of its inherent uncertainty, deriving conclusions that are reliable and from sufficient observations can be a problem. Generalizing, in other words: probabilistic forecasting from limited available data. An example sometimes given is: all the swans I’ve ever seen have been white, so therefore it would seem reasonable to conclude that all swans must be white… until, that is I see a black swan. Obviously, any one person’s experience must be limited, so any conclusions derived from them, must also be limited.
All generalizations are false, including this one, as Mark Twain famously observed. I’m not sure I’d go that far, though. I think George Bernard Shaw was closer to what I have learned about depending on one’s own experience to the exclusion of competing views: Beware of false knowledge; it is more dangerous than ignorance.