The effects of acupressure on labor pains during child birth: randomized clinical trial 1

ABSTRACT Objective: to analyze the effects of acupressure on the sanyinjiao point for pregnant women in labor at public maternity wards. Method: single-blind controlled clinical trial, randomly done employing a pragmatic profile. We selected 156 pregnant women in their ≥ 37 week/s, who had cervical dilations of ≥ 4 cm and with two or more contractions in 10 minutes. The pregnant women were randomly divided into three groups at a university hospital in the suburbs of Sao Paulo, Brazil, in order to receive either acupressure treatment, a placebo or participate as part of a control group. The acupressure was applied on the sanyinjiao point during the contractions for 20 minutes. Then the intensity of the pain was evaluated using the Visual Analogue Scale (VAS). Results: The averages for the pain measured using the VAS were not different for the three groups that were a part of the study (p-value=0.0929), however they were less in the acupressure groups immediately after receiving the treatment (p-value=<0.0001). This was also the case where the treatment lasted for 1 hour (p-value=0.0001). This was the case in comparison with placebo and control groups. Conclusion: the use of acupressure on the sanyinjiao point is a useful way to alleviate pain in a non-invasive manner. It can improve the quality of care given to pregnant women in labor. Register: RBR-9mhs8r.


Introduction
Child birth is considered to be a natural phenomenon however the pain that it can bring is both subjective and complex involving physiological, cultural and psychosocial aspects. Currently there are a lot of studies aimed at looking to reduce the pain in child birth (CB) emphasizing non-medicinal treatments that are less invasive and more humanized. These are being developed by nurses and obstetricians.
In traditional Chinese medicine (TCM) various alternative methods are used to alleviate pain mainly through acupuncture, moxibustion, acupressure and the use of herbs. Acupressure functions in the same way as acupuncture in that it seeks to maintain the balance of energy in the various channels that circulate in the body -called meridians -that are connected to the specific body organs, but without the use of needles.
Specific points in the hands and fingers are stimulated (sometimes combining points) to have the best effect in alleviating pain or in putting someone in a relaxed state 4) .
The effects of acupressure on the pain during child birth has been studied in controlled and randomized studies (CRS) done in Asian countries (3,(5)(6) and in the Middle East (7)(8)(9)(10)(11)(12) . Three acupuncture points were identified for acupressure in the CREs: the Sanyinjiao point (SP6), the Hegu point (IG4) and the Zhiyin point (B67). The TCM theory is that these points contain the action that effects the activity in the uterus and which can induce the CB. Advice is also given for it to be used in cases of shoulder dystocia and prolonged CB (6) .
The SP6 point is believed to have the ability to control some aspects of the reproductive organs being in the case of dystocia and prolonged CB. It is located in the spleen-pancreas meridian, four fingers above the internal malleolus in the front part of the tibia ( Figure 1).  The size of the sample was estimated through considering the proposed calculation method for the nonpaired (14) t test. We looked at the percentage differences in the pain using the Visual Analogue Scale (VAS) before and after the treatment in the three studies (6,8,11) . For the calculations, we adopted a level of significance equal to 5% and a power of 80%, except for studies that also showed results after 60 minutes. In these cases For conducting evaluations on the pain we opted for the VAS model which is a rising scale from 0 10, 0 meaning no pain to 10 which is the worst pain felt.
The patients registered their pain using a picture of a grimacing face and writing down a number next to it.
The VAS was used and reused immediately after the treatment (VAS20) and 60 minutes after the treatment, once consent had been given by the pregnant women in labor to participate in the study. The SP6 group with the pregnant women in labor received deep pressure (± 5kg) with fast decompression applied to their thumbs which did not bring about any discomfort. The TG group received a superficial touch that was of very low intensity (± 100g) (15) . In both groups the contact was at the SP6 bilateral point, during the contractions, in one period of 20 minutes.
The researcher that was responsible for applying the acupressure went through 32 hours' worth of training.
A child-cushioned electronic anthropometric scale was used to control and to put consistent pressure on the thumps until the researcher could apply such pressure for the SP6 and TG groups.
The pregnant women in labor obtained normal obstetrical treatment. Where the study was carried out, the following was permitted: the presence of someone to accompany the pregnant lady, the use of methods other than drugs such as taking a shower, massages in the lower back region and breathing exercises as well as liberty of movement (in cases where this did not go against medical advice).
All of the pregnant women in labor where encouraged during the CB to breath in and out deeply in the direction of the thorax during the contractions and the intervals in orde for their bodies to be totally relaxed (slow thorax-abdomen breathing rhythm) (16) .
A questionnaire was developed to obtain sociodemographical and clinical data. The content was analyzed in relation to its validity by five experienced analysts who had experience in obstetrics and/or in Bonferroni correction was used for the variables where the comparisons between the groups and those that were measured took place in one evaluation period.
This divided the significant level by the number of comparisons. The significant level of 1.67% was adopted where the variable was measured in three periods and we compared the groups at every stage. In relation to the VAS variable, aside from comparing the groups at every period we also measured the periods for every group.
With this we adopted the significant level of 0.83% for this variable. Lastly for the multiple comparisons, the significant level was corrected, following the same criteria.

Results
156 pregnant women in labor were used in this study and they were distributed equally in three groups.
None of them were taken out due to the process of There are no differences between the groups with reference to the variables studied. The obstetrical characteristics in Table 2 show the variables of the groups that can influence the responses for pain by the pregnant women.  In relation to intravenous analgesics or those that were intra-musculary administered during the CB, the number was small due to their use being discouraged in obstetric wards. The medications used were either: dipyrone 1gr, meperidine 50mg or tramadol 50 mg.
They were used on two women in the TG, two in the CG and only one in the SP6 group.
The analgesia epidural or the spinal anesthesia were available for women depending on their need. Their groups. The SP6 group and the CG group showed seven contractions compared with six in the TG.
VAS was used to evaluate the pain and for predeveloped questions. The women were able to classify their perception of the pain (Table 3). (closing the door). This will inhibit the pain and reduce discomfort for the lady that receives the treatment (20) .
The women did not use a lot of intravenous or intramuscular analgesic in this study. We also noted this in other previous studies (6) . They were used a great deal for all the women in the three CRSs (7,11,21)

Conclusion
The results show that the use of acupressure on the SP6 point is a complementary method that is noninvasive and can alleviate pain during childbirth, without presenting any adverse effects for pregnant women in labor and neonate women.
Acupressure is a useful way to alleviate pain and it can be easily be put into practice in medical institutions with a view to improving the quality of care given to pregnant women in labor who would like a natural birth.
However the effect of the treatment in the reduction of pain is small, which suggests that acupressure may be more effective where there are cervical dilations up to 8 cm and there is cephalic presentation.
Acupressure is an alternative for women that prefer to use methods that do not involve drugs and side membrane, the cervical dilations and the number and intensity of the contractions. We noted during the treatment fewer contractions in the TG group in relation to the SP6 and CG group that received the acupressure.
Through an evaluation of the pain we saw a significant reduction in the group that received acupressure in the SP6 point in comparison with the TG and CG groups. The average for the VAS was less in the two evaluations after the treatment in the SP6 group.
This data is similar to the previous CRS (7,10)  Korea where the dilations were between 9 and 10 cm.
The points were close for the CG.
The other three CRS (3,6,8) evaluated the SP6 point on pain. The VAS score was not subsequently inferior to the base values. Its rise, however, was greater for the women with the placebo. These studies did not include a third group. Pain in the CB is gradual. Also the fact that the pain did not get worse shows the effectiveness of the care given.
The participants in the TG showed, on average, a lower rise in the VAS even though on the whole there were no significant differences. This may be due to the superficial touch on the SP6 bilateral point which is a common practice for palpation points and body energy points that stimulates the flux of energy (3) . Continuous support for pregnant women in labor can reduce complaints of birth pains, favoring the development of the CB as note in a revision of Cochrane (18) .
The effect of acupressure on pain is not entirely clear physically and biochemically speaking. An explanation based on TCM called the "Gate-control theory of pain" was given in 1965 which talks about cutaneous tactile stimulation used to alleviate pain (19) . The theory states that acupressure activates mechanoreceptors that provoke the thick fibers (A-alfa and A-beta) and which direct them to shut the door whilst the fine fibers