Does routine induction of labour at 41 weeks reduce the rate of caesarean section?

www.sogc.org/jogc/abstracts/full/200907_Obstetrics_3.pdf

Does Routine Induction of Labour at 41 Weeks Really Reduce the Rate ofCaesarean Section Compared With Expectant Management?

Heidi Pavicic, RN, MN,1 Kathy Hamelin, RN, MN,1 Savas M. Menticoglou, MDCM21Women's Health Program, University of Manitoba, Winnipeg MB2Department of Obstetrics and Gynaecology and Reproductive Sciences,University of Manitoba, Winnipeg MB

Objective:
It is contended that routine induction of labour at 41 completed weeks of gestation reduces, or at least does not increase, a woman's chance of Caesarean section (CS),compared with expectant management. We wanted to know if this was true in our own hospital.

Methods:
We performed a retrospective review of 1367 nulliparouswomen who had reached 41+0 weeks undelivered with a live,singleton, fetus with a cephalic presentation. The womencomprised two non-randomized contemporaneous cohorts: in onegroup, expectant management was planned, and in the secondgroup the intention was to induce labour at 41 weeks. The primaryoutcome measure was the rate of CS in each group.

Results:
Of 645 women in whom expectant management was planned, 17.7% delivered by CS.
Of 722 women in whom induction of labour was planned, 21.3% delivered by CS(P = 0.09).
Of the total of 907 women in whom expectant management was planned or who laboured spontaneously before planned induction could be carried out, 16.6% delivered by CS.
Of 460 women in whom induction was planned and actually carried out, 25.4% delivered by CS (P = 0.001).

Conclusion:
There may be a case for routine induction of labour at 41+0 weeks if the aim is to eliminate the 1 in 1000 chance of fetal death. The best antenatal fetal monitoring cannot prevent deaths from massive abruption or intrapartum asphyxia.
But almost 1000 inductions of labour at 41+0 weeks will be needed to prevent a single fetal death. Our study suggests that the contention that routine induction of labour at 41+0 weeks reduces a woman’s chance of CS is untrue, and that the opposite may be true: that inducing labour actually may increase the nulliparous woman’s chance of undergoing Caesarean section.

J Obstet Gynaecol Can 2009;31(7):621-626