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Sir,

Thank you for the opportunity to reply to the comments by Jackson and Paterson-Brown. Because of the known difference in labour patterns between multiparous and nulliparous women, we presented the data separately in our report1. In fact, when the multiparous and nulliparous women are analysed together, the total duration of labour was still significantly shorter in the misoprostol group (P= 0.006) (Table 1). A significant difference was seen for both the first (P= 0.002) and second stages of labour (P= 0.004). Although the induction-to-delivery interval was shorter in the misoprostol group, this difference did not reach statistical significance (6.5 h vs. 10.1 h; P > 0.05).

Table 1.  Outcome of labour in the misoprostol and oxytocin groups. Values are given as mean (SD) and comparison by Mann- Whitney U test.
 Misoprostol (n= 40)Oxytocin (n= 40)P
  1. *P < 0.05.

First stage (h)4.4 (2.8)7.9 (5.3)0.002*
Second stage (h)0.5 (0.3)0.9 (0.7)0.004*
Third stage (min)1.9 (3.4)4.7 (4.8)0.007
Total duration of labour (h)4.7 (2.6)8.6 (5.6)0.001*
Induction to delivery interval (h)6.5 (3.2)10.1 (5.4)0.05

Of the 13 women in the misoprostol group who developed tachysystole, five (38.5%) received only a single dose and the others received two doses. In the current trial of Jackson and Paterson-Brown, a different route (vaginal) was used for administration of the drug which might have contributed to the difference in the incidence of tachysystole. The bioavailablility of vaginally-administered misoprostol is about three times that of oral misoprostol2. It was therefore not surprising that 73% of their women with tachysystole had received only a single dose, compared with 38.5% of the women with tachysystole in our study. We recommend increasing the dosing interval to six-hourly instead of four-hourly as used in our study, not because this could prevent the tachysystole in the 38.5% of women who had only one dose, but to reduce the incidence of tachysystole in the other 61.5% of women who required two doses.

The objective of our study was to examine the pattern of labour and uterine activity, and not to compare the caesarean section rates between the groups; for this outcome a very large sample is required as pointed out by Jackson and Paterson-Brown.

References

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  2. References
  • 1
    Ngai SW, Chan YM, Lam SW, Lao TT. Labour characteristics and uterine activity: misoprostol compared with oxytocin in women at term with prelabour rupture of the membranes. Br J Obstet Gynaecol 2000; 107: 222227.
  • 2
    Zieman M, Fong SK, Benowitz NL, Bankster D, Darney PD. Absorption kinetics of misoprostol with oral or vaginal administration. Obstet Gynecol 1997; 90: 8891.