Objective: To estimate what level of additional fetal risk women and their caregivers in late pregnancy considered acceptable to avoid a cesarean and achieve a vaginal birth.
Methods: Six hundred women in late pregnancy and 294 obstetric consultants, registrars, midwives, and medical students were recruited to the study. With the assistance of a visual probability aid representing 10,000 births, they were asked to consider what level of fetal risk of death or serious disability they would consider acceptable to avoid cesarean and achieve vaginal birth.
Results: The median level of fetal risk deemed acceptable to achieve a vaginal birth for pregnant women was 10 per 10,000 births (95% confidence interval [CI] 10-13 per 10,000), although the range of responses was wide (1-5,000 per 10,000). Among staff, the median level of acceptable fetal risk was 13 per 10,000 births (95% CI 10-20 per 10,000). Women participating in lower intervention models of care, such as the birth center or team midwifery, were more tolerant of fetal risk (odds ratios [ORs] 2.1, 95% CI 1.6-2.9 and 1.5, 95% CI 1.0-2.3, for accepting a fetal risk of 20 per 10,000 or greater), whereas women with a complicated pregnancy were less tolerant of fetal risk (OR 0.7, 95% CI 0.5-0.9).
Conclusion: Pregnant women and their caregivers have a low tolerance for fetal risk associated with vaginal birth. This study demonstrates the difficulty of minimizing obstetric intervention rates in the face of high expectations for fetal outcome. Obstetric and demographic factors were found to significantly impact the "acceptable fetal risk" threshold, which highlights the importance of individualized counseling regarding mode of birth.
Level of evidence: III.