Reseach Updates 2011

Phys­i­cal activ­ity before and dur­ing preg­nancy and risk of ges­ta­tional dia­betes mel­li­tus: a meta-analysis.Tobia DK, Zhang C, van Dam RM, Bow­ers K, Hu FB. Dia­betes Care. 2010 Sep 27.

The researchers con­cluded that higher lev­els of phys­i­cal activ­ity prior to preg­nancy or in early preg­nancy are asso­ci­ated with a sig­nif­i­cantly lower risk of devel­op­ing GDM. The study search iden­ti­fied 7 pre-pregnancy and 5 early preg­nancy stud­ies, includ­ing 5 prospec­tive cohorts, 2 ret­ro­spec­tive case-controls, and 2 cross-sectional study designs. Pre-pregnancy phys­i­cal activ­ity was assessed in 34,929 total par­tic­i­pants includ­ing 2,813 GDM cases, giv­ing a pooled odds ratio of 0.45 (95% CI: 0.28–0.75) when com­par­ing the high­est vs. low­est cat­e­gories. Exer­cise in early preg­nancy was assessed in 4,401 total par­tic­i­pants includ­ing 361 GDM cases, and was also sig­nif­i­cantly pro­tec­tive (OR=0.76, 95%CI: 0.70, 0.83).

Aer­o­bic exer­cise dur­ing preg­nancy improves health-related qual­ity of life: a ran­domised trial. Mon­toya Ariz­a­baleta AV et al. J Phys­io­ther. 2010;56(4):253–8.

The researchers con­cluded that a super­vised 3-month pro­gram of pri­mar­ily aer­o­bic exer­cise dur­ing preg­nancy improves health-related qual­ity of life. The exper­i­men­tal group had improved their health-related qual­ity of life more than the con­trol group in the phys­i­cal com­po­nent sum­mary of the ques­tion­naire by 6 points, the phys­i­cal func­tion domain by 7 points, the bod­ily pain domain by 7 points and the gen­eral health domain by 5 points.

The exper­i­men­tal group com­pleted a 3-month super­vised exer­cise pro­gram, com­menc­ing at 16 to 20 weeks of ges­ta­tion. Each ses­sion included walk­ing (10 min), aer­o­bic exer­cise (30 min), stretch­ing (10 min), and relax­ation (10 min). The con­trol group con­tin­ued usual activ­i­ties and per­formed no spe­cific exer­cise.  The pri­mary out­come was health-related qual­ity of life assessed by the Colom­bian ver­sion of the Med­ical Out­come Study Short-Form Health Sur­vey at base­line and imme­di­ately after the 3-month intervention.

Effects of Yoga:

For more than 30 years, DTP has included exer­cise com­po­nents that are ele­ments of yoga (cen­ter­ing, deep breath­ing, mindfulness/transcendence, iso­met­rics and relax­ation), because these are mea­sur­able, effec­tive com­po­nents within a total fit­ness pack­age.  Car­dio­vas­cu­lar con­di­tion­ing is our cen­ter­piece — along with spe­cific strength work — since these pro­duce most of the ben­e­fits of pre­na­tal fit­ness. Due to the grow­ing pop­u­lar­ity of pre­na­tal yoga at the expense of car­dio­vas­cu­lar con­di­tion­ing and strength train­ing, we have been seek­ing cred­i­ble research evi­dence about yoga’s effect on preg­nancy, birth and recovery.

Despite the length of time it has been avail­able, there is lit­tle data to estab­lish yoga’s effi­cacy beyond reduc­ing some dis­com­forts and per­haps improv­ing body trust, often through the use of posi­tions, breath­ing skills and mind­ful­ness that are also com­mon child­birth prepa­ra­tion and com­fort mea­sures. The relax­ation ele­ment — achiev­able through any stan­dard alpha brain wave pro­duc­ing method — can help pro­mote pro­mote progress in early labor, as the Relax­ation Response (per Ben­son) is known to help the body release oxy­tocin in early labor (per Odent). How­ever, the only study of the cor­re­la­tion among labor onset, yoga and the length of the first stage was very small. It was per­formed in Thai­land and we can­not find any record of exactly what was per­formed dur­ing the six ses­sions over the course of pregnancy.

Yoga dur­ing preg­nancy: effects on mater­nal com­fort, labor pain and birth out­comes. Chunthara­pat S, et al. Com­ple­ment Ther Clin Pract. 2008 May;14(2):105–15. Epub 2008 Mar 4.

Effects of a pre­na­tal yoga pro­gramme on the dis­com­forts of preg­nancy and mater­nal child­birth self-efficacy in Tai­wan. Sun YC, et al. Mid­wifery. 2010 Dec;26(6):e31-6. Epub 2009 Feb 25.

This non-randomized study aimed to pro­vide yoga to prim­i­gravi­das in the third trimester of preg­nancy to decrease dis­com­forts asso­ci­ated with preg­nancy and increase child­birth self-efficacy. Low risk, seden­tary prim­i­gravi­das were tar­geted. The pro­gram was 12–14 weeks, with at least three ses­sions per week. Each work­out lasted for 30 min­utes. Pro­gram par­tic­i­pants reported sig­nif­i­cantly fewer preg­nancy dis­com­forts than the con­trol group (38.28 vs 43.26, z=-2.58, p=0.01) at 38–40 weeks of ges­ta­tion and exhib­ited higher out­come and self-efficacy expectan­cies dur­ing the active stage of labour (104.13 vs 83.53, t=3.24, p=0.002; 99.26 vs 77.70, t=3.99, p ? 0.001) and the sec­ond stage of labour (113.33 vs 88.42, t=3.33, p=0.002; 102.19 vs 79.40, t=3.71, p ? 0.001) com­pared with the con­trol group. Inter­est­ingly, the researchers con­cluded that the pro­vi­sion of book­lets and videos on yoga dur­ing preg­nancy may con­tribute to a reduc­tion in preg­nancy dis­com­forts and improved child­birth self-efficacy.

Effi­cacy of yoga on preg­nancy out­come. Naren­dran S, et al.  J Altern Com­ple­ment Med. 2005 Apr;11(2):237–44.

The only matched-control study we have seen that reports any ben­e­fi­cial out­comes for yoga par­tic­i­pants vs. con­trols was a small study con­ducted in India. Women par­tic­i­pated daily in super­vised 1-hour ses­sions, while con­trols walked. The daily yoga par­tic­i­pants’ out­comes were improved com­pared with con­trols, includ­ing a reduc­tion in IUGR, in con­junc­tion with infec­tion and PIH. It is impor­tant to keep in mind that these out­comes occurred in a set­ting where under-weight, over-work and infection-related com­pli­ca­tions are common.

It is inter­est­ing to note that aer­o­bic fit­ness pro­vides the same ben­e­fits as those seen in these stud­ies, while also reduc­ing the need for aug­men­ta­tion or other inter­ven­tions, as well as reduc­ing the risk of fetal distress.

Dur­ing the sec­ond stage of labor, the tran­si­tion to an ergotropic reflex pro­motes the release of oxy­tocin as the body changes from a parasym­pa­thetic state in the first stage to a sym­pa­thetic state in the sec­ond stage (that is why we call the end of the first stage tran­si­tion). The phys­i­ol­ogy of push­ing requires a very aggres­sive approach. Our in-house data sug­gest that we have found a bal­ance for help­ing women develop the nec­es­sary traits to accom­plish both the pas­sive state required by the first stage and the endurance capac­ity to become aggres­sive dur­ing expul­sion. We mea­sure this in the reduc­tion of our cesarean rate by 1/2 to 1/3 com­pared to the local population.

There is evi­dence of inverse risk for cesarean as the amount and inten­sity of aer­o­bic con­di­tion­ing increases. These stud­ies are also fairly small, although they are numer­ous and have pro­duced con­sis­tent results con­cern­ing dose-effect. There is grow­ing inter­est within the health care field that sup­port­ing pre­na­tal aer­o­bics could help reduce the cesarean rate. There is no infor­ma­tion from any cred­i­ble sources con­cern­ing the rela­tion­ship of yoga to type of birth. The only avail­able sta­tis­ti­cal infor­ma­tion is the coin­ci­den­tal cor­re­la­tion that as the cesarean rate has risen in the U.S., so has the pop­u­la­tion that par­tic­i­pates in pre­na­tal yoga.

Yoga remains an illu­sive sub­ject of study. So much depends on who is teach­ing and what they are teach­ing. Unlike aer­o­bics, strength, range of motion, relax­ation response, bal­ance, coor­di­na­tion and train­ing speci­ficity — all of which we can pre­scribe and mea­sure — the pop­u­lar term yoga has lost mean­ing. How much of exactly what is nec­es­sary to pro­duce effects? What are those effects? Are they ben­e­fi­cial? These ques­tions are yet to be answered.