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Sir,

We appreciate the interest in our paper about misoprostol-induced labour once more, and are pleased to address the concerns of Dr Wuntakal and Dr Erskine.1

The efficacy of misoprostol in the management of postpartum haemorrhage because of uterine atony is not questioned and there is robust evidence in literature about it. This apparent paradox, however, can be resolved knowing that the pharmacokinetics and pharmacodynamics of misoprostol, on uterine myometrium and cervical collagen are quite different in the antepartum from the postpartum periods.

In our original work, we did not analyse blood loss by parity, but when this was done, the duration of labour was non-significantly shorter among multiparous women, but this again correlated with initial Bishop score. Parity per se neither correlated with the duration of labour nor the postpartum blood loss.

We agree that ambulation during the first stage of labour might be preferred by some women, but here we are discussing induced labour, and not spontaneous childbirth. Intravenous drip is the only recommended method of administering oxytocin during labour. We also agree that different routes of administration might be preferred by different women, vaginal examination, however, would be inevitable for assessment of progress of labour. Vaginal misoprostol can be self administered. Most important is that the effect of misoprostol is not different using different routes of administration,2 justifying the speculation that the same results of this study would have been obtained using oral or sublingual route.

The Cochrane review of Kelly et al.3 entitled ‘oxytocin alone for cervical ripening and labour induction’ evaluates oxytocin efficacy in induction of labour. In this review, women with unfavourable cervix induced by oxytocin alone had higher incidence of unsuccessful vaginal delivery than those who had pre-induction ripening by vaginal prostin. Postpartum blood loss was not a main outcome measure in this review.

In the trial of Prager et al.,4 when 25 μg vaginal misoprostol were used for induction, the mean induction delivery interval was 17.3 hours and maternal outcome was not different from balloon catheter and dinoprostone although postpartum blood loss was not clearly stated. These results indicate that even if the 25 μg dose did not correlate with blood loss, this was on the expense of efficacy, because whatever the impact of misoprostol on the course of labour it is likely to be dose dependent.

Finally, we think that all of the suggestions recommended in the letter would be good ideas for further studies.

References

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  2. References
  • 1
    Wuntakal R, Erskine K. Evaluation of postpartum blood loss after misoprostol-induced labour. BJOG 2009;116:1535.
  • 2
    Alfirevic Z, Weeks A. Oral misoprostol for induction of labor. Cochrane Database Syst Rev 2006:CD001338.
  • 3
    Kelly AJ, Tan B. Intravenous oxytocin alone for cervical ripening and induction of labour. Cochrane Database Syst Rev 2001:CD003246.
  • 4
    Prager M, Eneroth-Grimfors E, Edlund M, Marions L. A randomized controlled trial of intravaginal dinoprostone, intravaginal misoprostol and transcervical balloon catheter for labour induction. BJOG 2008;115:144350.