What it is
A thin catheter is passed through the cervix and one (Foley) or two (Cook) balloons are inflated with sterile saline. The gentle pressure helps the cervix soften and dilate to about 3–4 cm, at which point the balloon falls out on its own. It's often used before Pitocin when the cervix is not yet ripe, and is one of the few induction methods considered generally acceptable after a prior cesarean.
Evidence review links
Each link opens the full review on the publisher's site in a new tab.
Possible benefits
- No medication — lower risk of tachysystole (contractions that are too strong)Review sources ↓
- Can be used at home overnight in some settingsReview sources ↓
- Compatible with VBAC / TOLAC in most guidelinesReview sources ↓
- Often shortens the total induction time when followed by PitocinReview sources ↓
Possible risks
- Placement can be uncomfortable and may cause bleeding or crampingReview sources ↓
- Small risk of accidentally breaking the water, infection with prolonged use, or displacing the baby's headReview sources ↓
- Doesn't cause active labor on its own for most people — usually paired with PitocinReview sources ↓
Alternatives
- Prostaglandins (misoprostol / Cervidil) for cervical ripeningReview sources ↓
- Membrane sweepReview sources ↓
- Starting with Pitocin alone if the cervix is already favorableReview sources ↓
Current evidence
ACOG and multiple randomized trials support mechanical ripening as safe and effective, with outcomes generally comparable to prostaglandins and a lower risk of tachysystole. Evidence Based Birth has a dedicated review/podcast episode on Foley and Dilapan-S for cervical ripening during induction. See: https://evidencebasedbirth.com/evidence-on-dilapan-s-and-foley-for-cervical-ripening-during-an-induction/
Where the evidence is clear · where people may choose differently
For most topics, guidelines from ACOG, WHO, and other major bodies broadly agree on the core safety points (when to act in an emergency, informed-consent standards, monitoring baselines). Where reasonable people — and even guidelines — differ tends to be around thresholds (when to start or stop something), preferences (comfort, environment, support), and values (how you weigh small risks against benefits). Use the questions below to explore those pieces with your care team.
Educational only. Your care team can help you weigh what applies to your specific situation.
Questions to ask your care team
- ?Is the Foley done inpatient or can I go home with it?
- ?How long do you leave it in before the next step?
- ?What happens if it doesn't fall out on its own?
- ?Is this an option for my VBAC?
Universal questions (works for any decision)
A short BRAIN-style set you can bring to any conversation about interventions, monitoring, or care decisions.
- ?Why are you recommending this now — is it urgent, routine, or optional?
- ?What happens if we wait an hour (or longer) before deciding?
- ?What signs would tell us this is working — or that we need to change course?
- ?What are the alternatives, including doing nothing?
- ?What would you recommend if this were your family?
- ?What would change your recommendation?
Sources & provenance
Tap a source to open the original guideline or review in a new tab.
- ACOG Practice Bulletin 107: Induction of Labor — ACOG
- EBB 153: Pros and Cons of the Foley and Dilapan-S for Cervical Ripening During an Induction — Evidence Based Birth
Written in plain language from general guidance published by the listed organizations. No verbatim excerpts; editors should re-verify wording and citations against current source versions before publish.
Last reviewed: 2026-07-02
Further reading — canonical references
Read the source material directly. Each link opens the publisher's own current guidance in a new tab — cross-check what we summarize against what they say.
Tier 1 · Clinical guidelines
- ACOG guidance on “Induction: Foley / Cook Balloon (Mechanical Ripening)”ACOG — U.S. clinical guidelines from the American College of Obstetricians and Gynecologists.
- NICE guidance on “Induction: Foley / Cook Balloon (Mechanical Ripening)”NICE — UK clinical guidelines — often useful when ACOG and WHO differ.
Tier 2 · Systematic reviews
- Cochrane reviews on “Induction: Foley / Cook Balloon (Mechanical Ripening)”Cochrane Library — Systematic reviews — top of the evidence stack when available.
- PubMed studies on “Induction: Foley / Cook Balloon (Mechanical Ripening)”PubMed — Primary research — filter by review or meta-analysis for strongest evidence.
Educational only. Guidelines evolve — the linked publisher pages will reflect newer guidance than any static snapshot.
Version history — v1.0.0
v1.0.0 · 2026-07-02 · LlaMamma editors
Initial Foley/Cook balloon topic added with ACOG and Evidence Based Birth links.
Sources: ACOG Practice Bulletin 107; Evidence Based Birth Foley/Dilapan-S review
New guidance from ACOG, WHO, Evidence Based Birth, or other listed sources is recorded here and can be updated remotely without a new app release.