Labour

Definition of Labour

Labour is known as the process by which the products of conception are expelled from the uterine cavity after the 24th week of gestation or pregnancy.[1] Labour typically occurs between the 37th and 42nd week of gestation and can be classified into three stages.[2]

Stages of Labour

First Stage

The first stage of labour begins with the onset of regular rhythmic contractions and culminates when the cervix is fully dilated to ~ 10 cm.[2] During early labour, contractions are fairly weak, occurring 15 - 20 minutes apart and lasting ~ 30 seconds in duration.[2]  Contractions begin in the fundus of the uterus and travel downwards and outwards towards the cervix.[2] This phenomenon is known as fundal dominance, whereby the contractions are strongest in the upper uterine segment and weakest in the lower uterine segment.[2]  Another phenomenon, known as polarity, also occurs during contractions, whereby the upper uterine segment contracts while the lower uterine segment dilates to accommodate the baby.[2] Following each contraction, the uterine muscle fibres undergo retraction.[2] Instead of relaxing completely the muscle fibres remain shortened allowing for gradual progression of the baby downward through the uterus.[2] At the same time contractions are occurring the cervix will begin to dilate and will undergo effacement (or thinning of the uterus).[2] As the cervix dilates, the mucus plug formed during pregnancy is lost and women might notice a bloody mucoid discharge.[2]

The first stage of labour can further be divided into 3 phases: the latent phase, the active phase and the transitional phase.

  1. Latent Phase: This phase lasts for approximately 6-8 hours, achieving a cervical dilation of ~3-4 cm.[2]
  2. Active Phase: In this phase, cervical dilation occurs more rapidly, reaching a total dilation of ~7 cm. In primigravida mothers (or first-time mothers), dilation occurs at a rate of 1cm/hour and in multigravida mothers (or second-time mothers), dilation occurs at a rate of 1.5 cm/hour.[2]
  3. Transitional Phase: Cervical dilation slows down in this phase and the cervix reaches full dilation (10 cm).[2]

Second Stage

The second stage of labour begins when the cervix is fully dilated and ends when the baby is born.[2]  Stage two can be divided into two phases: the latent phase and the active phase. The average duration of stage two is 50 minutes for primigravida mothers and 20 minutes for multigravida mothers.[3]

During the latent phase, the mother will feel no urge to push.[2] In this phase, the baby's head will continue to descend down through the uterus via the force of the uterine contractions until it is visible at the vaginal orifice.[2] Contractions are longer and stronger in stage two, however, they are less frequent to allow the mother time to recover between each contraction.[2] As the baby is descending through the uterus it will change its position frequently to navigate the curvature of the birth canal.[2] Several pelvic tissues will be displaced as the baby continues to descend through the birth canal. The bladder is pushed up into the abdominal cavity, the rectum flattens along the sacral nerve, the levator ani muscles are thinned out, and the perineum is stretched.[2] 

Once the baby's head is visible at the vaginal orifice, the active phase of stage two begins. In this phase, there is an increased pressure exerted on the rectum and pelvic floor from the fetal head.[2] This results in the initiation of the Ferguson Reflex, which provides the mother with the urge to push.[2] Women with epidurals might not feel this urge to push as strongly.[2] The mother can adopt different birthing positions to increase the diameter of their pelvic outlet and allow for accommodation of the baby's head upon delivery.[2] However, this decision may be influenced by the delivery personnel and whichever position provides them with the greatest access to the baby. During pushing, women should be encouraged to avoid prolonged breath-holding and excessive pushing as this can interfere with placental perfusion and compromise the fetus.[1]

The mother will typically push with her contractions. In between each contraction and push, the uterus relaxes and the baby recedes. At a certain point, the perineum will start to bulge and the baby’s head will become visible. This is termed crowning. Once the head is born, the shoulders and body follow with the next contraction.

During crowning, there is intense stretching of the perineal tissue, increasing the risk of perineal trauma. Perineal tears can be classified into four degrees:[2]

  • First Degree Tear: involves the skin of the fourchette (the inner fold of the vulva) only[2]
  • Second Degree Tear: involves the skin of the fourchette, the perineum and the perineal body[2]
  • Third Degree Tear: involves the skin of the fourchette, the perineum, the perineal body and the anal sphincter[2]
    • 3A: less than 50% of the external anal sphincter is torn
    • 3B: greater than 50% of the external anal sphincter is torn
    • 3C: internal anal sphincter is torn
  • Fourth Degree Tear: involves the skin of the fourchette, the perineum, the perineal body, the external and internal anal sphincters, and the anal epithelium.[2]

Alternatively, an episiotomy can be performed. This is a surgical incision made to the perineum to increase the diameter of the pelvic outlet. It would be the equivalence of a second-degree tear.[2]

Third Stage

The third stage of labour involves the delivery of the placenta and the control of bleeding to prevent a hemorrhage.[2] This stage normally lasts from 5 to 30 minutes in duration but may last as long as one hour. Separation and delivery of the placenta occurs spontaneously via contractions and these contractions are typically less painful than what is experienced in stage two.[2] Once the placenta is delivered, control of bleeding can be achieved naturally or pharmacologically.[1][2] Naturally, control of bleeding can occur through ligatures, which involves the contraction of the oblique muscles to constrict the uterine blood vessels, through the application of pressure from the uterus to the placental site, and through blood clotting whereby the uterus will be covered with a fibrin mesh.[2] Placement of the baby onto the breast can also help to achieve placental separation and assist with control of bleeding via the release of oxytocin. Following delivery, the placenta is examined for completeness.[2]

Physiotherapy Management

Transcutaneous Electrical Stimulation (TENS)

TENS provides a non-pharmacological method for pain relief.[6] It has been used in clinical practice to relieve both acute and chronic pains as well as treat various conditions including dysmenorrhea and back pain.[7][8]

During labour, electrodes are typically positioned over the areas of the skin that overlie the thoracic (T10), lumbar (L1) and sacral nerve endings (S2-S4).[2][6][7][9] Accurate placement of electrodes is vital in maximizing pain relief.[2] Once turned on, the TENS unit will emit low-voltage impulses.[6] The mother may operate the unit herself to control the frequency and intensity of the impulses during labour.[2][6]  Typically, the application of TENS is most effective when commenced during the early stages of labour.[2][10] However, it is important to note that it may not provide sufficient pain relief for some women on its own.[2] When using the TENS unit it is important to screen the mother for any contraindications (i.e. cardiac pacemaker).

The mechanism by which TENS relieves pain is unknown, however, two theories have been proposed:

  1. The Gate Control Theory:[11] Transmission of pain is inhibited by stimulation of the afferent nerve fibres that carry impulses towards the CNS.[6][11]As afferent nerve fibres are stimulated, the pathway for painful stimuli is closed by the “gate” in the spinal cord that controls transmission to the brain.[6][11] TENS stimulates afferent nerve fibres which can inhibit the transmission of painful stimuli from the uterus, vagina, and perineum during labour.[12]
  2. Endorphin Release: TENS increases the release of endogenous opiates in the cerebrospinal fluid (endorphins and encephalins), which can increase an individual's threshold to pain and increase their feeling of well-being.[13][14]

Although TENS has been involved in childbirth since the 1970s,[12] its use during labour still remains inconclusive in the literature. Several systematic reviews assessing the role of TENS for pain relief during labour have stated that there is limited evidence to support the analgesic effect of TENS during labour.[6][15][16] Some evidence states that women using TENS are less likely to rate their pain as severe, however, the results among these studies are not consistent.[6] Furthermore, evidence has found that TENS has no effect on labour outcomes, including mode of delivery, length of labour, or well-being of mothers and their babies.[6] 

Despite the discrepancies in the literature, TENS is still perceived well by many women, and women studied report being willing to use TENS again in a future labour.[6] Due to this, a debate has arisen regarding whether this satisfaction is due to the analgesic effect of the TENS itself or the sense of control it provides to women.[6]  Green and Baston (2003) have stated that a woman's satisfaction with the childbirth experience is affected by their sense of control during labour, specifically control during their contractions.[17] The ability for women to operate the TENS unit by themselves during labour could, therefore, explain its popularity.[6]  For this reason, women should be educated on the possible benefits of TENS during labour and given the choice to use it if they feel it will be helpful.[6]

Massage Therapy

Massage therapy, which involves the manipulation of the body’s soft tissue, can be performed by a massage therapist, a physiotherapist, a midwife, or a woman's partner. Massage therapy may be used to relax tense muscles, potentially providing pain relief during labour.[18] Additionally, given that it involves physical contact with the women, some evidence has stated that it can have a role in relaxation and emotional stress.[7][19][20]

Massage can encompass a wide variety of techniques including deep tissue massage, trigger point massage, neuromuscular massage, etc. [21][18] Different techniques may be preferred by different women. For example, massage over the lumbosacral area may be more preferred by a woman who is experiencing back pains during labour.[18] Alternatively, effleurage over the abdominal region may provide women with stress relief as soft touch and light stroking have been associated with the release of oxytocin.[18][22] No adverse effects have been noted in the literature regarding massage therapy.[18]

The proposed theories behind the mechanism by which massage therapy provides pain relief includes: improving blood flow and oxygenation of tissues, reduction of cortisol and norepinephrine levels, an increase in serotonin levels, endorphin release or via the pain gating theory.[11][18][23][24]

While a few trial studies have identified massage therapy as an effective technique to reduce the amount of pain and anxiety that is experienced during the first stage of labour,[19][23][25]more high-quality evidence regarding massage therapy's role in labour is still required. This is supported by a Cochrane review published by Smith and Colleagues (2018)[18] who found low-quality evidence regarding the analgesic effect of massage therapy during the first stage of labour and low-quality evidence during the second and third stage of labour.[18]Furthermore, massage therapy had no clear effect on the length of labour or on pharmacological pain.[18]

Thermotherapy and/or Cryotherapy

Warm compresses are used during labour with the intention to reduce perineal pain and increase comfort during labour.[26][27][28][29][30][31]Heat promotes dilation of blood vessels, increases blood flow, and interrupts the transmission of pain.[32][33][34] Dahlen and colleagues (2009)[35] reported that women who received a warm compress during the second stage of labour were significantly less likely to report the pain they experienced as “bad” or as the “worst pain in my life” and had a statistically significant lower mean pain score than women who received standard care.[35]  Other studies with smaller sample sizes have supported the use of warm packs.[26][27][28][36][37][38][39] Similarly, immersion in warm water has been supported in the literature to reduce labour pains.[40][41][42]When considering the use of warm compresses during the first stage of labour, a review by Smith and colleagues (2018)[18] reported that low-quality evidence exists.[18] During the third phase of labour, heat could increase a mother’s comfort, increase endorphin and oxytocin release, and potentially allow for earlier delivery of the placenta.[43] 

Ganji and colleagues (2013)[43] examined the effects of simultaneous heat and cold on managing labour pains and reported that local warming with intermittent cold packs to the low back, lower abdomen, and perineum could reduce labour pains during the first and second phases of labour.[43] No adverse effects on maternal and fetal outcomes were reported.[43] The use of ice packs during labour has been supported by the works of Waters and Raisler who found a reduction in reported labour pain when ice massage was applied to the Hugo point (large intestine meridian).[43][44]

The use of heat or cold therapy provides a safe and inexpensive method for pain relief and provides mothers with an increased satisfaction with their labour experience.[35][43] As previously mentioned, the greater satisfaction with childbirth could be a result of the perceived sense of empowerment and control a mother feels while using these modalities during labour.[17][43]

Accupuncture and/or Accupressure:

Acupuncture is a technique that involves the insertion of needles into different points of the body, whereas acupressure involves applying pressure to different points of the body using one’s thumb or fingers.[45]

The role of acupuncture for labour induction has been documented by three different studies.[46][47][48] Furthermore, two other studies documented the ability for acupuncture to initiate contractions in women at term.[49][50] The speculated mechanism behind acupuncture's role in labour induction is through the release of oxytocin and an increase in the parasympathetic stimulation of the uterus.[51] However, a more recent systematic review conducted by Smith and colleagues (2017)[45] found no evidence for acupressure or acupuncture to induce labour and reduce the need for cesarean section.[45]

When considering pain relief, Smith and colleagues (2020)[52] stated that acupuncture may increase a woman's satisfaction with pain relief during labour and may help to reduce pain during labour.[52] However, it should be noted that the evidence that supports acupuncture during labour is low in quality.[52] Higher-quality evidence is still needed when considering the use of acupuncture or acupressure during labour.[52] 

Relaxation Techniques

Relaxation techniques aim to help women cope with their labour pains by slowing down breathing, lowering blood pressure, and providing a sense of wellbeing.[53] Relaxation techniques encompass guided imagery and progressive relaxation and breathing techniques.[53]

Guided imagery involves using one’s imagination as a therapeutic tool.[54] During guided imagery, the individual can substitute an unpleasurable or painful sensation with a pleasurable and relaxing experience to decrease the intensity of the painful stimulus.[53] For example, the individual can imagine replacing pain with a comforting sensation such as heat or cold.[53]  

Progressive muscle relaxation, developed by Edmund Jacobson (1938)[55], involves consecutive tensing and relaxation of the different muscle groups in a toe to head direction until relaxation of the entire body is achieved.[53][55] Both guided imagery and progressive muscle relaxation provide an easy to learn and teach technique that is safe to the soon to be mother.[53]

Relaxation techniques are associated with lower pain intensity during the latent phases of labour.[53] However, their effect is not clear during the active phases of labour.[53] Although low-quality evidence exists for the use of relaxation techniques, education on relaxation techniques have increased a woman's satisfaction with pain relief during labour in the literature.[53]

Breathing Techniques

Breathing techniques can interrupt the transmission of pain from the uterus to the brain by decreasing sympathetic activity and providing emotional regulation.[53][56] Slow and deep breathing has been encouraged during labour to increase relaxation and decrease pain.[57][58][59]

Examples of breathing techniques that have been assessed in the literature include soft sleep breaths performed in between contractions, blissful belly breaths performed during contractions for pain relief, cleansing calming breaths to be used following contractions during the transition period of labour, and gentle birth breaths to be used during the second stage of labour to encourage descent of the baby and avoid active pushing.[60] 

Other breathing exercises in the literature include deep diaphragmatic breathing,[61] slowed inhalation (~ 5 sec in duration) during the first stage of labour,[57][62] shallow breathing during the active phases of labour[62], pursed-lip breathing during contractions,[57] and the “pant-blow” technique during pushing in the second stage of labour.[62]

Boaviagem and colleagues (2017)[57] demonstrated that the use of various breathing techniques (i.e. slow deep breathing, pursed-lip breathing, post-exhalation pause) in isolation had no effect on anxiety, pain, fatigue and maternal satisfaction compared to routine care.[57] However, several studies have reported that breathing exercises in combination with other techniques (i.e. massage, relaxation techniques) are effective in reducing the perception of pain by women during labour.[60][62][63] This literature stresses the importance of a multifactorial approach in labour pain management. Breathing may provide an effective strategy for pain relief in combination with other techniques (i.e guided imagery, massage, relaxation).[57]

Perineal Massage

Perineal massage provides a method to gently stretch the pelvic floor in preparation for birth. A Cochrane review written by Aasheim and colleagues (2017)[64] states that there is moderate-quality evidence in favour of perineal massage to reduce the incidence of third and fourth-degree perineal tears while performed during the second stage of labour.[64] Additionally, there is also some evidence to support the idea that perineal massage is associated with an increased number of women with an intact perineum following labour.[64]

Other studies have assessed the use of perineal massage during pregnancy as a protective measure against perineal trauma.  Specifically, perineal massage during the last month of pregnancy can enable the perineal tissue to expand more easily during birth.[65] Through appropriate education from a pelvic floor physiotherapist, perineal massage can be performed by the woman or her partner for 10 minutes, as little as once or twice a week starting from 35 weeks.[65] A review by Beckmann and Garrett (2006)[65] reported that antenatal (during pregnancy) perineal massage was associated with an overall reduction in the incidence of perineal trauma requiring suturing, as well as the incidence of episiotomies.[65] However, no benefits have been reported regarding the incidence of first/second and third/fourth-degree tears.[65] Antenatal perineal massage is generally well-received by most women,[65][66] however some women may find that the massage can be uncomfortable during the first few weeks and may even experience a burning sensation.[65] Additionally, newer techniques of perineal massage involve the use of a massaging device. However, the effectiveness of massaging devices still needs to be explored.[65]

Positioning

The position a woman adopts during labour varies depending on which stage of birth they are in, whether they have received epidural anaesthesia and the risks and benefits that are associated with each position.

Birthing positions can be divided into two different categories: vertical/upright positions and horizontal or recumbent/semi-recumbent positions:[67]

Vertical/ Upright positions:[67]

  • Squatting: The mother is supported by a partner or a prop
  • Kneeling: The mother is kneeling with their trunk upright or palms resting on the ground/cushion
  • Sitting: The mother can sit on a bed or chair with their trunk leaning forward at a 45-degree angle

Horizontal/ Recumbent and semi-recumbent positions:[67]

  • Supine position: The mother is lying on her back or with her trunk slightly raised (less than 45 degrees from horizontal)
  • Lithotomy Position: The mother is lying flat on her back with legs raised in stirrups
  • Lateral Position: The mother is lying on her side with her upper leg close to her chest

The use of upright postures during the second stage of labour has been debated in the literature. Being in an upright posture during labour allows for the effects of gravity, promotes better alignment of the baby through the birth canal, increases strength of the uterine contractions, reduces the incidence of aortocaval compression (or compression of the inferior vena cava by the uterus when a pregnant woman is lying in a supine position), and increases the diameter of the pelvic outlet in the squatting and kneeling positions.[68] Despite these benefits, a semi-recumbent position is commonly used as it provides caregivers with increased access to the baby during birth, as well, most caregivers are trained to deliver babies using this position[68].

When comparing the risks and benefits of each position, Huang and colleagues (2019)[67] concluded that upright and lateral positions provide more benefits to mother and her baby during labour.[67] Lateral positions are associated with fewer perineal tears.[67] Upright positions are associated with less labour pain, shorter durations of the second stage of labour and fewer episiotomies.[67] However, whenever using the squatting and sitting position caregivers should be aware of the increased risk of perineal trauma.[67] Huang and colleagues (2019)[67] suggested that supine and lithotomy positions should be avoided unless preferred by the mother, as they increase the risk for severe perineal trauma, longer labour durations, and greater labour pains.[67]

During the first stage of labour, women are encouraged to adopt a forward-leaning posture.[2] A forward lean posture can facilitate the fetal head into a more favourable position for passage through the birth canal.[2] Furthermore, the forces of gravity associated with this position can help lead to the Ferguson Reflex which provides mothers with the urge to push in the second stage of labour.[2]

A review by Gupta and colleagues (2017)[68] stated upright positions were associated with a reduced duration of the second stage of labour, a reduction in assisted deliveries, a reduction in episiotomies, and lower risk for abnormal fetal heart rate in women who did not receive an epidural.[68] However, there was a noted increase in blood loss greater than 500 ml and second-degree perineal tears.[68] These findings were supported by Deliktas and Kukulu (2018)[69] who reported a decrease in forcep-assisted births, a decrease in the incidence in episiotomies, and an increased risk of postpartum blood loss.[69]

A review by Walker and colleagues (2018)[70] reported little to no difference between upright and supine positions on rates of cesarean sections, assisted birth, or length of the second stage of labour in women who had received epidural during labour.[70] There was also no difference in the number of perineal tears and the amount of excessive bleeding following labour.[70] This review also stated that women were slightly more satisfied with lying down positions.[70]

Despite these findings, more research is still needed to confidently recommend which birthing position is most favourable.[68] Women should be encouraged to give birth in whichever position feels most comfortable.[68] 

Education:

Approximately 90% of the stress and anxiety women experience during pregnancy is related to the process of childbirth and its risks.[71][72] Furthermore, anxieties and expectations can be moulded by the mother’s personal experiences, her culture, and societal views.[73][74][75][76] Fear and anxiety can increase muscle tension, further increasing the perception of pain during labour.[77] Fear and anxiety can have consequences on the baby, potentially leading to preterm birth, low fetal birth rate, and fetal hypoxia.[78] Physiotherapists, along with other healthcare professionals, can play a vital role in educating new mothers prenatally, antenatally, and postnatally about what they can expect to avoid these fears and anxieties.

The goal of antenatal education is to provide support and reassurance during pregnancy and to assess and treat any problems that arise during pregnancy.[79] Education should include information about postpartum care, newborn care, breastfeeding, intercourse during pregnancy, signs of complications and appropriate steps to take.[79] Education during pregnancy provides an opportunity for pregnant women to discuss any concerns they have with a healthcare professional.[79] Furthermore, education allows healthcare professionals to empower women during their pregnancy to develop their own unique set of coping strategies.[80] It is important to provide women with this opportunity as satisfaction with childbirth is linked to women’s sense of control and their participation in the decision-making process of their pregnancy.[17]

Although further research regarding antenatal education is still needed, studies have reported benefits of education to reduce fear and anxiety during pregnancy,[71][72][81] to increase a mother's self-confidence[71][72] and her satisfaction with pregnancy,[82] to decrease the incidence of false labour admissions,[81] and to increase partner involvement.[81]

For physiotherapists, this might include education about:

See also

Physical Activity and Pregnancy

Transcutaneous Electrical Nerve Stimulation (TENS)

Preconceptual care

Rebound Therapy

References

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