Labor Length Differences in Combination Ripening with 60 versus 30-mL Foley Inflation Volume: A Propensity Score-Matched Study

Abstract

Objective

Data support shorter time to delivery with 60 versus 30-mL Foley inflation for labor induction. Similarly, combination cervical ripening has a shorter time to delivery compared with single agents. To date, no study has evaluated incremental benefit of higher Foley volume in the setting of combination ripening methods.

Study Design

This is a secondary analysis of a prospective cohort study evaluating standardized induction management at two sites. Any cervical ripening method could be used. Site no. 1 used 60-mL Foley inflation, whereas Site no. 2 used 30 mL. For this analysis, patients were included if they underwent a term (≥37 weeks) induction from 2020 to 2022 with a singleton, intact membranes, and received combination methods of Foley and another agent. A 1:1 propensity score matching balanced baseline parameters.

Results

Of 4,295 inductions, 2,117 (49.3%) utilized combination cervical ripening methods. After propensity score matching, 1,480 were included. Even in the context of combined ripening and standardized induction, Foley inflation to 60 mL was associated with a 3-hour shorter labor length than 30 mL (14.6 [10.4–21.3] vs. 17.7 hours [12.4–24.4], p < 0.001). When censored for cesarean, patients who received 60-mL Foley inflation delivered 70% faster than those who received 30 mL (hazard ratio: 1.73 [1.36–2.21]). There was no difference in cesarean, maternal morbidity, or neonatal morbidity.

Conclusion

Even when using combined cervical ripening methods, 60-mL Foley inflation is associated with reduced time to delivery as compared with 30 mL without increasing morbidity.

Key Points

• No prior study has evaluated incremental benefit of higher Foley volume.

• Combined cervical ripening with 60-mL Foley is associated with reduced time to delivery.

• Combined cervical ripening with 60-mL Foley is not associated with differences in morbidity.

Keywords

cervical ripening - Foley - induction - labor length - propensity score

Contributors' Statement

Rebecca F. Hamm: Conceptualization, data curation, formal analysis, funding acquisition, investigation, methodology, software, visualization, writing—original draft, writing—review and editing. Jennifer A. McCoy: Data curation, formal analysis, methodology, writing—review and editing. Antoilyn Nguyen: Data curation, investigation, project administration, writing—review and editing. Lisa D. Levine: Conceptualization, formal analysis, funding acquisition, investigation, methodology, supervision, writing—review and editing.

Ethical Approval

The project was approved by the University of Pennsylvania Institutional Review Board as quality improvement, and written informed consent was thereby waived.

Publication History

Received: 29 January 2026

Accepted: 16 February 2026

Accepted Manuscript online:
19 February 2026

Article published online:
26 February 2026

• References

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