Dispelling Myths on Pregnancy Exercise

At regular intervals, it becomes necessary to dispel two persistent myths that are often perpetuated by well-meaning care providers. Both of them were debunked long ago, in research literature that is readily available and about which I have written a great deal, including in my chapters on Women and Exercise (editions 3 & 4) and Health Promotion in Varney’s Midwifery (edition 5), in posts on the DTP website, on my Twitter feed (@anncowlin), on DTP’s Facebook page and in a textbook.

DTP_mover1_pregnantThe more common myth is that pregnant women should never let their pulse get over 140 beats per minute. But, more on that one at another time. That was an ACOG guess in 1985 that long ago (1994) was rescinded.

The other is that pregnant women should never begin a new exercise regimen, but only modify (i.e., reduce) what they are already doing. What brings me to write this blog after a blog break (to respond to our expanding pre/postnatal fitness teacher training program) is that this evening I was told the latter myth was promoted by a CNM at a recent nearby conference. A childbirth education colleague alerted me to this occurrence and also to the happy response by an unknown person in the audience, who chose to differ with the midwife, citing Dancing Thru Pregnancy® as her example!! Thank you to this responder.

Let me address – yet again – the issue of whether it is safe for pregnant women to begin an exercise regimen after they become pregnant. The caveat I offer at the outset is that doing so should be under the supervision of a knowledgeable certified pre/postnatal fitness specialist. Within the profession, the resolution of this question is generally agreed to be the Cochrane Review conducted in 2002, which found that aerobic fitness can be improved or maintained in pregnancy. Improvement requires increasing the level of aerobic challenge. More recently, researchers concluded “….pregnant women benefit from regular physical activity the same way as non pregnant subjects…” and that “…[t]he adoption or continuation of a sedentary lifestyle during pregnancy may contribute to the development of certain disorders such as hypertension, maternal and childhood obesity, gestational diabetes, dyspnoea, and pre-eclampsia.” (Melzer et al. Physical activity and pregnancy: cardiovascular adaptations, recommendations and pregnancy outcomes. Sports Med. 2010 Jun 1;40(6):493-507. 

Put another way, the female is not put together to be sedentary in pregnancy. It is only in recent decades that this is an option. Until the mid 20th Century, activities of daily living required physical fitness, and obesity was rare, along with sedentary behavior. In the last few decades, those who are knowledgeable about the interactions of pregnancy and exercise, and who have the experience of teaching movement to this population, have come to understand how to present activities that improve the factors that improve maternal and fetal outcomes.

Those who are extremely well-versed in the field all agree that cardiovascular (aerobic) fitness during the 6 – 12 month pre-pregnancy period may be the greatest pregnancy enhancement a woman can have. Why? Because endothelial function is greatly enhanced, oxidative stress is reduced, and vascularity is increased by aerobic fitness, and these capacities underly healthy implantation and placental development (see Research Updates 2001-2005, Winter 2005 and Winter 2004 and Update on Immune Function). Barring that, beginning early in pregnancy is helpful because placental development is still underway. Barring that, mild to moderate aerobic activity introduced by 25-30 weeks will produce cardiovascular enhancement by the time of labor. My caveat goes here, too.

All conditions mediated by inflammation are a problem in pregnancy. Physical fitness is a major preventive strategy for inflammation, and pregnancy does not stand in the way.

 

 

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