Prolonged pregnancy: the management debate.

A prospective trial was conducted to compare the effects of conservative management of prolonged pregnancy (conservative group) with routine induction of labour at 42 weeks' gestation (active group) in otherwise uncomplicated pregnancies. Of the 402 pregnancies studied, 207 (51%) were allocated to conservative management and 195 (49%) were allocated to have labour induced. The groups were well matched for age, parity, and smoking habits. One hundred and sixty six (80%) of the patients in the conservative group went into spontaneous labour. Of the remainder, two underwent elective caesarean section, 19 had labour induced because of clinical concern, and the remaining 20 had labour induced at the patient's own request. One hundred and twenty five (64%) of the patients in the planned active group underwent induction of labour. Of the remaining 70, 49 went into spontaneous labour and 21 (11%) asked that they should not have labour induced. Comparison of the two groups showed no difference in the length of the first stage of labour but a trend towards an increased need for intervention for fetal distress (p less than 0.06) in the active group. There were no differences in the length of the second stage, the need for intervention, or the mode of delivery. In terms of Apgar scores the neonatal outcome was not significantly different between the two groups, but a greater proportion of the babies (15% v 8%) in the active group required intubation. Umbilical cord venous pH estimated in the last 183 consecutive deliveries in the study showed a significantly lower mean value in the active group (p less than 0.05). There was no difference in birth weight between the two groups. Two deaths occurred in the study. There was a stillbirth in the conservative group at 292 days after massive abruption, and one neonatal death in the active group owing to multiple congenital abnormalities. The outcome for mother and baby in patients from both groups who went into spontaneous labour was generally good. The outcome for patients for whom conservative management was planned but induction became necessary was no different from that of patients who underwent planned induction at term. Thus from our results we can find no evidence to support the view that women with normal prolonged pregnancy should undergo routine induction of labour at 42 weeks' gestation.