Buccal or sublingual misoprostol for cervical ripening and induction of labour

Not enough evidence to say if misoprostol administered under the tongue or in the cheek is safe for induction of labour.

Sometimes labour is started artificially (induction) because of concerns for the well-being of either the baby or the mother. A drug called misoprostol has previously been used either by being put in the mother's vagina or by being swallowed. It is now suggested that placing it under the tongue or in the cheek may be more effective. There were not enough studies to say whether there might be important adverse effects. More research has been called for.

Authors' conclusions: 

Based on only three small trials, sublingual misoprostol appears to be at least as effective as when the same dose is administered orally. There are inadequate data to comment on the relative complications and side-effects. Sublingual or buccal misoprostol should not enter clinical use until its safety and optimal dosage have been established by larger trials.

[Note: The 17 citations in the awaiting classification section of the review may alter the conclusions of the review once assessed.]

Read the full abstract...

This is one of a series of reviews of cervical ripening and labour induction using standardised methodology. Misoprostol administered by the oral and sublingual routes have the advantage of rapid onset of action, while the sublingual and vaginal routes have the advantage of prolonged activity and greatest bioavailability.


To determine the effectiveness and safety of misoprostol administered buccally or sublingually for third trimester cervical ripening and induction of labour.

Search strategy: 

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (8 December 2003), the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 4, 2003), and bibliographies of relevant papers.

We updated the search of the Cochrane Pregnancy and Childbirth Group's Trials Register on 28 July 2009 and added the results to the awaiting classification section.

Selection criteria: 

Randomised controlled trials comparing buccal or sublingual misoprostol used for third trimester cervical ripening or labour induction with placebo/no treatment or other methods listed above it on a predefined list of labour induction methods.

Data collection and analysis: 

A generic strategy was developed to deal with the large volume and complexity of trial data relating to labour induction. Data were extracted onto standardized forms, checked for accuracy, and analysed using RevMan software.

Main results: 

Three studies (502 participants) compared buccal/sublingual misoprostol respectively with a vaginal regimen (200 µg versus 50 µg) and with oral administration (50 versus 50 µg and 50 versus 100µg).

The buccal route was associated with a trend to fewer caesarean sections than with the vaginal route (18/73 versus 28/79; relative risk (RR) 0.70; 95% confidence interval (CI) 0.42 to 1.15). There were no significant differences in any other outcomes.

When the same dosage was used sublingually versus orally, the sublingual route was associated with less failures to achieve vaginal delivery within 24 hours (12/50 versus 19/50; RR 0.63, 95% CI 0.34 to 1.16), reduced oxytocin augmentation (17/50 versus 23/50; RR 0.74, 95% CI 0.45 to 1.21) and reduced caesarean section (8/50 versus 15/50; RR 0.53, 95% CI 0.25 to 1.14), but the differences were not statistically significant.

When a smaller dose was used sublingually than orally, there were no differences in any of the outcomes.