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Induction of labour for improving birth outcomes for women at or beyond term
Gülmezoglu AM, Crowther CA, Middleton P
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Induction of labour in normal pregnancies at or beyond term
A normal pregnancy lasts about 40 weeks from the start of the woman"s last menstrual period, but anything from 37 to 42 weeks is considered within the normal range. Births before 37 weeks are considered premature because these babies often have breathing difficulties and other problems as some of their organs will not yet be fully matured, e.g. their livers. Births after 42 weeks seem to carry a slightly increased risk for the baby, and this review sought to find out if induction of labour at a prespecified time could reduce this increased risk or not. There are currently no tests that can tell if a baby would be better to be left in the womb or be induced and born, so arbitrary time limits have been suggested. The review of trials found 19 studies involving almost 8000 women given induction of labour at various times from 38 weeks to over 42 weeks" gestation; some were quite old trials and the quality was variable. The review grouped the trials by induction at (1) 37 to 40 weeks; (2) 41 completed weeks; and (3) 42 completed weeks, compared with waiting to a later date. There were fewer baby deaths when a labour induction policy was implemented after 41 completed weeks or later. However, such deaths were rare with either policy. Women"s experiences and opinions about these choices have not been adequately evaluated.

This is a Cochrane review abstract and plain language summary, prepared and maintained by The Cochrane Collaboration, currently published in The Cochrane Database of Systematic Reviews 2009 Issue 1, Copyright © 2009 The Cochrane Collaboration. Published by John Wiley and Sons, Ltd.. The full text of the review is available in The Cochrane Library (ISSN 1464-780X).
This record should be cited as: Gülmezoglu AM, Crowther CA, Middleton P. Induction of labour for improving birth outcomes for women at or beyond term. Cochrane Database of Systematic Reviews 2006, Issue 4. Art. No.: CD004945. DOI: 10.1002/14651858.CD004945.pub2.

This version first published online: October 18. 2006


Abstract
Background
As a pregnancy continues beyond term the risks of babies dying inside the womb or in the immediate newborn period increase. Whether a policy of labour induction at a predetermined gestational age can reduce this increased risk is the subject of this review.

Objectives
To evaluate the benefits and harms of a policy of labour induction at term or post-term compared to awaiting spontaneous labour or later induction of labour.

Search strategy
We searched the Cochrane Pregnancy and Childbirth Group"s Trials Register (June 2006).

Selection criteria
Randomized controlled trials conducted in women at or beyond term. The eligible trials were those comparing a policy of labour induction to a policy of awaiting spontaneous onset of labour. Trials comparing cervical ripening methods, membrane stripping/sweeping or nipple stimulation without any commitment to delivery within a certain time were excluded.

Data collection and analysis
Two review authors independently evaluated potentially eligible trials and extracted data. Outcomes are analysed in two main categories: gestational age and cervix status.

Main results
We included 19 trials reporting on 7984 women. A policy of labour induction at 41 completed weeks or beyond was associated with fewer (all-cause) perinatal deaths (1/2986 versus 9/2953; relative risk (RR) 0.30; 95% confidence interval (CI) 0.09 to 0.99). The risk difference is 0.00 (95% CI 0.01 to 0.00). If deaths due to congenital abnormality are excluded, no deaths remain in the labour induction group and seven deaths remain in the no-induction group. There was no evidence of a statistically significant difference in the risk of caesarean section (RR 0.92; 95% CI 0.76 to 1.12; RR 0.97; 95% CI 0.72 to 1.31) for women induced at 41 and 42 completed weeks respectively. Women induced at 37 to 40 completed weeks were more likely to have a caesarean section with expectant management than those in the labour induction group (RR 0.58; 95% CI 0.34 to 0.99). There were fewer babies with meconium aspiration syndrome (41+: RR 0.29; 95% CI 0.12 to 0.68, four trials, 1325 women; 42+: RR 0.66; 95% CI 0.24 to 1.81, two trials, 388 women).

Authors" conclusions
A policy of labour induction after 41 completed weeks or later compared to awaiting spontaneous labour either indefinitely or at least one week is associated with fewer perinatal deaths. However, the absolute risk is extremely small. Women should be appropriately counselled on both the relative and absolute risks.