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44.1Cardiotocograph trace in precipitate labour. Precipitate labour may also predispose to uterine rupture in parous women, particularly if there is a pre-existing caesarean section scar.įig. Placental blood supply is via intramyometrial blood vessels which are constricted during the contraction, and excessively long or frequent contractions reduce the chance of recovery in the short times when blood flow is returned (Fig. Precipitate labour resulting from either spontaneous hypercontractility or uterine hyperstimulation may lead to fetal distress.

With prostaglandins, hyperstimulation is also a significant risk but is less likely if their administration is intravaginal, rather than oral, intracervical or directly extra-amniotic. While the licensed maximum dose is currently 20 mU/min, some clinicians support the use of regimens up to 40 mU/min. The appropriate dose of syntocinon remains controversial, but there is good evidence for starting at a low dose, around 0.5–4 mU/min, and increasing over 4 or 5 h to 12 mU/min.

The choice of dosage regimens for each represents a compromise between efficacy and the risk of hyperstimulation. Both syntocinon (synthetic oxytocin that is administered by injection or infusion) and prostaglandins may be implicated. Uterine hyperstimulation occurs much more commonly, however, and by definition is caused by the use of oxytocics. Spontaneous uterine hypercontractility may be associated with placental abruption (see p. The contractions may be excessively long in duration or be excessively frequent and there is a risk of fetal hypoxia due to interference with the placental blood supply. Spontaneous hypercontractility is rare, perhaps occurring in only 1:3000 pregnancies. It is subdivided into ‘true’ cephalopelvic disproportion if the head is in the correct position and ‘relative’ cephalopelvic disproportion if the obstruction is caused by the head presenting in a position other than occipitoanterior. Slow labour may result from inadequate uterine activity, cephalopelvic disproportion, or more commonly, a combination of the two.Ĭephalopelvic disproportion refers to how well the fetal head fits through the pelvis and may occur if the fetal head is too big or the pelvis too small. Precipitate labour has been defined as expulsion of the fetus within less than 3 h of the onset of contractions and results from uterine overactivity. In practice, overactivity presents as rapid painful contractions often associated with fetal distress, and inadequate uterine activity as absent or slow cervical dilatation. It is tempting to refer to uterine ‘overactivity’ as that which results in labour progressing too quickly, and ‘inadequate’ uterine activity as that which is insufficient to provide adequate progress, but the rate of progress has no precise definition either and is dependent on parity. Hypertensive disorders Maternal outcome Precipitous labor.Abnormal uterine activity has no clear definition, partly because the range of normal uterine activity itself has no clear definition. No significant differences were noted between the two groups regarding maternal or neonatal complications on both nulliparous and two-parous women.Īlthough precipitous labor was associated with hypertensive disorders in singleton vertex deliveries, it was not associated with maternal or neonatal outcomes. Using a multivariate analysis, precipitous labor in nulliparous women was independently associated with teenagers (adjusted OR: 1.71, 95% CI: 0.99 - 2.95, P = 0.049), preterm delivery (adjusted OR: 1.77, 95% CI: 1.16 - 2.70, P < 0.01) and hypertensive disorders (adjusted OR: 1.77, 95% CI: 1.19 - 2.65, P < 0.01), while in two-parous women, it was independently associated with hypertensive disorders (adjusted OR: 2.64, 95% CI: 1.33 - 5.24, P < 0.01). We examined the clinical characteristics and outcomes by comparing patients with precipitous labor and those with labor of normal duration in 0 and two-parous singleton pregnant women. We retrospectively examined our cases of precipitous labor to identify the clinical significance and perinatal outcomes following precipitous labor in singleton vertex deliveries.Ī retrospective population-based study was conducted comparing women with singleton precipitous labor and those with labor of normal duration.

Precipitous labor is defined as expulsion of the fetus within less than 3 hours of commencement of regular contractions.