Chapter 39 Care in the third stage of labour
The period from the birth of the baby until expulsion of the placenta and membranes is known as the third stage of labour. During this phase of the birthing process, the mother and child meet face to face for the first time. It is a time of great importance, when the actions of those present can have a long-term effect on developing family relationships and successful breastfeeding. It is also a time when the placenta will separate from the uterine wall, descend into the lower uterine segment and be expelled together with the membranes.
Traditionally, this period of childbirth has been regarded as ‘hazardous’ because of the risk of excessive bleeding; haemorrhage is a major cause of maternal death in the world (Khan et al 2006). However, currently within the UK, a very small number of women die as a result of excessive bleeding (Lewis 2007). This low rate of haemorrhage has been attributed to the prophylactic or routine use of active management during the third stage of labour for all women.
Active management is a package of care which includes the administration of an oxytocic drug, early clamping and cutting of the cord, and the speedy delivery of the placenta, usually by controlled cord traction (NICE 2007).
While the benefits of active management cannot be questioned for women at risk of postpartum haemorrhage, its indiscriminate use for women at low risk experiencing normal birth has been challenged (Harris 2001, Soltani 2008). Active management is not without risk and the component of active management which reduces blood loss has still not been clearly identified. A more targeted approach for active management has therefore been suggested, rather than its indiscriminate use for all women (Harris 2001, Soltani 2008), as currently there is insufficient evidence to support a clear recommendation.
An alternative to active management is expectant management, also called ‘passive’, ‘physiological’, or ‘natural’ management. This is a package of care where there is no active intervention in the normal physiological processes. It is characterized by activity on the part of the woman in birthing the placenta and membranes herself; the midwife’s role is one of ‘watchful waiting’.
In achieving this, midwives need to have an understanding of the physiology of the third stage and be able to develop partnerships with women to achieve successful delivery of the placenta and membranes with the appropriate rather than indiscriminate use of intervention.
It is suggested that women often are not given information about the third stage and do not choose how it will be managed. If women are to benefit from controlling their birth experience, then this should include the third stage of labour. A discussion should ideally take place antenatally and include the benefits and limitations of both active and expectant management. Following the discussion, the woman’s choice should be recorded clearly in her notes.
If women are to have a real choice, then consideration needs to be given to educating and supporting midwives in clinical practice and in developing a reflective analytical approach to discussions about the third stage which take place between midwives and women.
The third stage of labour is not really a stage at all. It is an extension of what has gone before (that is, the process of giving birth) and what will happen afterwards (the control of bleeding and the return of the uterus to its non-pregnant state). During labour, the uterine muscles contract and retract under the influence of naturally produced oxytocin. These muscles continue to contract and retract during the third stage to expel the placenta and membranes. The control of bleeding is brought about by the same physiological processes.
Separation of the placenta usually begins with the contraction that delivers the baby’s trunk and is completed with the next one or two contractions. As the body of the baby is delivered, there is a marked reduction in the size of the uterus because of the powerful contraction and retraction which take place. The placental site therefore greatly diminishes in size. Initially, placental separation was thought to be brought about by the bursting of decidual sinuses under pressure and the subsequent forming of a retroplacental blood clot which tore the septa of the spongiosa layer of the decidua basalis, detaching the placenta from the uterine wall (Brandt 1933). However, Dieckmann et al (1947) and more recently Herman et al (1993) suggest separation is caused by the active placental site uterine wall thickening and reducing in size, causing the placenta to ‘shear off’. Krapp et al (2000, 2003) describe three phases to the third stage of labour (Fig. 39.1). These three phases have now been widely accepted as describing the process of placental detachment and expulsion.
Figure 39.1 Phases in the third stage of labour. A. Latent phase: characterized by a thick placenta-free wall and thin placental site wall. B. Detachment phase: characterized by a gradual thickening of the uterine wall over the site of placental attachment. This process can be monophasic (a constant shearing-off movement) or multiphasic (which is characterized by pauses between phases of active detachment). C. Expulsion phase: the uterine wall is uniformly thickened and drives the placenta into the lower segment for expulsion.
Figure 39.2 The mechanism of placental separation. A. The placenta before the child is born. B. The placenta partially separated immediately after the birth of the child. C. The placenta completely separated. D. The placenta expelled and the uterus strongly contracted and retracted.
If the umbilical cord remains intact during the third stage, blood can pass to and from the infant until cord pulsation has ceased. The amount of blood gained or lost by the baby will depend on its position, with the potential for a net gain of 80 mL (Yao & Lind 1974). It is suggested that if the cord is clamped early, the resulting extra fetal blood retained in the placenta prevents it from being so tightly compressed by the uterus. As a result, contraction and retraction of the uterus may be less effective, and maternal blood loss increased, leading to a greater retroplacental blood clot being formed. Botha (1968) does not consider the formation of a retroplacental blood clot a physiological process. Rather, it occurs as a result of this intervention. Late cord clamping has also been associated with benefits for the infant (Hutton & Hassan 2007) (Box 39.1).
Benefits and risks associated with delayed cord clamping in the newborn
Detachment of the membranes begins in the first stage of labour, when separation occurs around the internal os. In the third stage, complete separation takes place assisted by the weight of the descending placenta, peeling them from the uterine wall.
The placenta appears fetal surface first, like an inverted umbrella with the membranes trailing behind. Any blood lost during the third stage will collect on the maternal surface of the placenta and be encased by the membranes. Over 80% of placentae are delivered in this way (Akiyama et al 1981).
Less commonly, the placenta slips from the vagina sideways and the maternal surface appears at the vulva first. Midwives often use the term ‘dirty Duncan’ for this type of presentation because more bleeding is seen vaginally – blood escapes immediately from the placental site because it is not encased in the membranes. This is often associated with slower separation of the placenta and ragged membranes.
Figure 39.4 How the blood vessels run between the interlacing muscle fibres of the uterus. A. Muscle fibres relaxed and blood vessels not compressed. B. Muscle fibres contracted, blood vessels compressed and bleeding arrested.
Any factor that interferes with the normal physiological processes can influence the outcome of the third stage of labour (see Box 39.2). This includes a variety of complications of pregnancy and childbirth as well as the actions of individual midwives. Oxytocic drugs given prior to and during the third stage of labour also influence events. A woman’s ability to avoid complications will also be based on her general health and by avoiding predisposing factors, such as anaemia, ketosis, exhaustion, and hypotonic uterine action.
Factors that may interfere with the physiological processes of the third stage of labour
Commonly, midwives describe two ways of managing the third stage: active management and expectant management. However, difficulties remain in defining what these terms mean, as midwives practise both methods in a variety of different ways (Harris 2005). The most commonly described form of each management will be outlined here with discussion about where variation may take place. The woman and her midwife will have discussed options for the third stage during the antenatal period and again during labour and made a decision over which management she would like.
Expectant management is one of ‘watchful anticipation’ and draws upon the normal physiological processes to bring about expulsion of the placenta and membranes. The woman is active during this process and the midwife’s role is a passive one involving close observation and encouragement.
Whichever position a woman chooses to give birth in, the newborn infant will be placed either on the bed/floor covering between the woman’s legs or on the woman’s abdomen, depending on her choice. Early skin-to-skin contact is advantageous in maintaining the infant’s temperature, in promoting successful breastfeeding and in supporting development of mother–infant attachment (Moore et al 2007). The midwife then steps back to leave the woman and her family to experience undisturbed the powerful first meeting with their new baby, while continuing to observe the wellbeing of the infant and maternal vaginal blood loss.
There is some debate about when the umbilical cord should be clamped and cut. The potential benefits and risks to the mother and infant of delayed cord clamping (McDonald & Middleton 2008) are being considered alongside the routine use of active management which normally incorporates immediate clamping and cutting of the cord (NICE 2007, WHO 2007). In accordance with the principles of non-intervention in expectant management, Inch (1985) suggests that ideally the cord should be left intact until the placenta and membranes are completely expelled, as this enables compaction and compression of the placenta and retraction of muscle fibres to occur unhindered. There may also be beneficial effects of continued delivery of oxygenated blood to the newborn infant via the cord (Hutchon 2006), particularly in those born prematurely or asphyxiated. In a study of premature infants conducted by Kinmond et al (1993), a 30-second delay in cord clamping with the infant held 20 cm below the introitus was associated with improved outcome for the baby. A more recent study in term neonates has linked a delay in cord clamping of 2 minutes with significantly higher mean corpuscular volume, ferritin and total body iron stores in the infant up to 6 months of age (Chaparro et al 2006). Early cord clamping has also been associated with fetomaternal transfusion, of particular importance in women who are rhesus negative (Lapido 1972). Enkin et al (2000) suggest that free bleeding of the cut end of the severed umbilical cord reduces the risk of fetomaternal transfusion. Placental cord drainage has also been associated with a reduction in the length of the third stage of labour (Soltani et al 2005).
If the cord is short, this may prevent a woman from holding her baby. In these circumstances, the woman may choose to have the cord clamped and cut once it has stopped pulsating (approximately 5–10 minutes after the baby is born).
Usually, whichever position a woman gives birth in, she will choose to sit once the baby is born. This allows her the opportunity to touch, hold and examine her baby. Skin-to-skin contact and breastfeeding should be encouraged as this aids separation and expulsion of the placenta through endogenous oxytocin release.
As the uterus begins to contract again, the woman will usually indicate this and may have an urge to bear down. The midwife may also notice abdominal changes; the fundus rises up and becomes more globular. The separated placenta may be seen as a bulge, similar to a full bladder, just above the symphysis pubis, with the well-contracted uterus sitting above it. In addition, a gush of blood per vagina and cord lengthening may occur. There is no necessity to palpate the abdomen unless there is cause for concern or the midwife suspects there may be some delay. Encouraging the woman to adopt an upright position at this time will lead to rapid expulsion of the placenta and membranes. Care needs to be taken when assisting the woman to move into another position, as she will have the baby in her arms. Standing, squatting and sometimes using a toilet, bucket or bedpan can be used.
The placenta is delivered by maternal effort. Normally, the woman in an upright position will feel the placenta as it descends to the pelvic floor, which triggers an urge to push, or the placenta will just fall out under the influence of gravity.
The midwife’s role is to let the woman know what is happening, to encourage her to adopt an upright position, and to advise her to listen to what her body is saying (to push or bear down if she wants to). A flat hand placed across the lower abdomen may assist the woman to birth the placenta, as the counterpressure compensates for poor muscle tone. The placenta and membranes are then delivered either onto the bed/floor or into a bedpan/toilet/bucket. If the membranes trail behind, they can be eased out of the vagina by turning the placenta to make a rope of the membranes, by applying gentle traction on the membranes with the fingers (usually in an up-and-down motion), or by asking the woman to cough. Once the placenta is completely expelled, the time is noted, to calculate the length of the third stage for recording later. The midwife then palpates the abdomen to ensure the uterus is well contracted and there is no excessive bleeding. The placenta and membranes can then be checked in front of the parents if they wish and any cord blood taken if the woman is rhesus negative.