Tuesday, August 01, 2006
Induction of Labour
Are you comingup on your "due date" and beginning to hear rumblings of induction from your health care providers and well meaning friends and family. Here is some information to help you make informed decisions around your birth...
Synthetic oxytocin administered intravenously in labour acts very differently from a labouring woman's intrinsic oxytocin. First, the uterine contractions produced by IV [oxytocin] are very different from natural contractions—possibly because it is administered continuously rather than in a pulsatile manner—and can cause detrimental effects to the baby in utero.
A woman's uterine contractions can occur too close together, leaving insufficient time for the baby to recover, and [synthetic oxytocin] also causes the resting tone of the uterus to increase. Such effects can produce abnormal fetal heart rate (FHR) patterns, fetal distress (leading to cesarean section) and even uterine rupture. As well, oxytocin augmentation stimulates uterine contractions out of proportion to cervical dilatation, compared to a natural labor: this increases the possibility of a "failed induction," where a woman's cervix fails to dilate and a cesarean becomes necessary.
...oxytocin, whether synthetic or not, cannot cross from the body back to the brain through the blood-brain barrier. This means that when it is administered in any way except directly into the brain, it cannot act as the hormone of love. It does, however, generate negative feedback—that is, receptors in the labouring woman's body detect high levels of oxytocin and so signal her brain to reduce production. We know that women who labor with an oxytocin infusion are at increased risk of postpartum haemorrhage, because their own oxytocin production has been shut down.
What we do not know, however, are the psychological or psychoneuroendocrine effects of giving birth without the peak brain levels of oxytocin that nature prescribes for all mammalian species.
In one study, women who had synthetic oxytocin augmentation did not experience an increase in beta-endorphin levels in labour, indicating the complexities that may result from interference with any of the hormonal systems in labour.
Other research has suggested that exogenous oxytocin may pass through the placenta unchanged, which implies that the baby's oxytocin system may also be disrupted by administration of synthetic oxytocin in labor.
Michel Odent notes, "Many experts believe that through participating in the initiation of his own birth, the fetus may be training himself to secrete his own love hormone..." Odent speaks passionately about our society's deficits in our capacity to love self and others, and he traces these problems back to the time around birth, especially to interference with the oxytocin system.
— Sarah Buckley, excerpted from "Undisturbed Birth: Nature's Blueprint for Ease and Ecstasy," Midwifery Today Issue 63
Induction is a minefield, a setup for complications. An induced labor forces the baby out before the body is ready; before the complex hormone interaction has primed the cervix; and often before the baby has reached his full intrauterine maturity. We have drugs now that can produce contractions and soften the cervix; but this is only a small part of the complicated process of labor. We can make a woman have contractions, but we don't always succeed in forcing her body to release the baby and give birth. If we start a labor with chemicals, we may very well have to finish the labor with the surgeon's scalpel.
In some studies, induction raises the risk of cesarean by 800 percent. [Electronic fetal monitoring (EFM)] must be used in all chemical induction methods because of the risk of hypertonic contractions and fetal distress. [EFM] alone increases the risk of cesarean and of vacuum extraction or forceps [use]. Amniotomy increases the risk again. Cesarean for fetal distress is even more common—whether the distress is real or a result of EFM artifact—since non-reassuring fetal heart tones are frequently observed. Meconium staining, meconium aspiration syndrome and even shoulder dystocia are directly associated [with] inductions. The rise in induction closely mirrors the rise in cesarean delivery, as does the rising incidence of post-cesarean rupture. A woman with prior cesarean is unlikely to suffer a uterine rupture (odds are usually given under [one] percent). But if she is induced, her risk may rise to 2 percent to 4 percent.
— Gail Hart, excerpted from "Induction & Circular Logic," Midwifery Today Issue 63
Women need all of the information before making these imporatant decisions. Trust Birth.
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