Risk factors for shoulder dystocia: An engineering study of clinician-applied forces

Robert Allen, Jagadish Sorab, Bernard Gonik

Research output: Contribution to journalArticlepeer-review

83 Scopus citations


We report on engineering risk factors associated with clinician-applied forces during vaginal delivery of newborns. Specifically, we present and interpret data from a series of experiments using force-sensing devices on 29 randomly selected vaginal births, including two shoulder dystocia deliveries and one birth injury. The results indicate that clinician-applied peak forces are typically about 47 N for routine deliveries, 69 N for difficult deliveries, and 100 N for a shoulder dystocia delivery (P < .01). The time required to deliver fetal shoulders doubles for nonroutine deliveries (P < .01). In addition, impulse and rate of application of force distinguish between routine and nonroutine deliveries (P < .03). We conclude that, if properly perceived, force, force rate, and the duration of force are objective parameters that can be used in recognizing and managing shoulder dystocia and in predicting thresholds for birth injury.

Original languageEnglish (US)
Pages (from-to)352-355
Number of pages4
JournalObstetrics and gynecology
Issue number3
StatePublished - Mar 1991

ASJC Scopus subject areas

  • Obstetrics and Gynecology


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