Breech Presentation at 29 Weeks Gestation
Approximately 36-37% of fetuses are in breech presentation at 29 weeks gestation, with the vast majority spontaneously converting to cephalic presentation before term.
Prevalence Data
- At 22-26 weeks gestation, the breech presentation rate is 36.8%, which serves as the closest available data point to 29 weeks 1
- By term (≥37 weeks), only 3-4% of singleton fetuses remain in breech presentation at delivery 2
- In one study examining the 33rd gestational week specifically, 42% of fetuses identified as breech remained breech until delivery, while 58% spontaneously converted to vertex 3
Natural History of Spontaneous Version
- The majority of breech presentations identified in the late second and early third trimester will spontaneously convert to cephalic presentation before labor 1
- Approximately 96% of fetuses in breech presentation at 22-26 weeks will spontaneously convert to cephalic by term (only 4.2% remain breech at labor onset) 1
- Spontaneous version becomes progressively less likely as gestational age advances beyond 32-34 weeks 1, 3
Risk Factors for Persistent Breech at 29 Weeks
Several factors increase the likelihood that a breech presentation at 29 weeks will persist:
- Uterine malformations increase the risk of persistent breech 8.7-fold 1
- Fundal or lateral placental location increases risk 2.4-fold 1, 4
- Female fetal sex increases risk 1.4-fold 1
- Nulliparity (first pregnancy) is associated with higher persistence rates 1
- Oligohydramnios (low amniotic fluid) 3
- Shorter umbilical cord length 4
Clinical Implications
- At 29 weeks gestation, breech presentation should be documented but does not require immediate intervention, as spontaneous version is highly likely 1
- Serial ultrasound monitoring of fetal presentation is typically performed in the third trimester 3
- External cephalic version, if indicated, is generally not attempted until 36-37 weeks gestation when spontaneous version becomes unlikely 2