5.1 Background
In this stage of labour placental separation and expulsion take place; for the mother the main risks are haemorrhage during or after separation of the placenta, and retention of the placenta. Postpartum haemorrhage is one of the main causes of maternal mortality; the large majority of these cases occur in developing countries (Kwast 1991). The incidence of postpartum haemorrhage and retention of the placenta is increased if predisposing factors are present, such as multiple pregnancy or polyhydramnios, and complicated labour: augmentation of labour, obstructed labour, or vaginal operative delivery (Gilbert et al 1987). Postpartum haemorrhage and placental retention also occur more frequently if these complications were present in the obstetric history of the woman (Doran et al 1955, Hall et al 1987, WHO 1989). To a certain extent therefore it is possible to select during pregnancy and in the course of labour those women with an increased risk of complications in the third stage. But even in low-risk pregnancies and after an uneventful first and second stage of labour serious haemorrhage and/or placental retention may sometimes occur. The management of the third stage may influence the incidence of these complications, and the amount of blood lost. Several measures aiming at the prevention of complications have been proposed, have been tested in randomized trials and are discussed below.
5.2 Prophylactic use of Oxytocics
Oxytocics may be given prophylactically at various moments during the third stage. Most often they are administered intramuscularly immediately with the delivery of the anterior shoulder, or after delivery of the infant. The drugs usually given, and investigated in trials, are oxytocin and ergot derivatives like ergometrine, or a combination of the two, syntometrine (Daley 1951, McGinty 1956, Friedman 1957, Newton et al 1961, Howard et al 1964, Hacker and Biggs 1979, Rooney et al 1985, Prendiville et al 1988, Thornton et al 1988, Begley 1990). Both oxytocin and ergot derivatives decrease the estimated postpartum blood loss, but the effect of ergot seems to be somewhat less than the effect of oxytocin. The effect on retention of the placenta is not yet quite clear, although there are some data suggesting that routine oxytocics may increase the risk of retained placenta.
Complications of oxytocics are nausea, vomiting, headache and hypertension postpartum. These complications occur more often with ergot derivatives. Moreover, rare but serious maternal morbidity has been associated with oxytocics, especially with ergometrine: cardiac arrest and intracerebral haemorrhage, myocardial infarction, postpartum eclampsia and pulmonary oedema. Because these events are so rare, randomized trials cannot give useful information about the extent to which they may be attributed to oxytocics. The available evidence suggests that oxytocin is a better choice than ergot derivatives. Moreover, in tropical countries oxytocin is more stable than ergometrine or methylergometrine (Hogerzeil et al 1992, 1994).
Because in many developing countries the administration of oral tablets would be much easier, and the tablets would be more stable than injections under tropical conditions, a randomized study was undertaken to investigate the influence of oral tablets of ergometrine immediately after birth. The outcome was disappointing: compared with a placebo the medication had little demonstrable effect on blood loss after childbirth (De Groot et al 1996).
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