Which of the following statements about breech birth is true: is breech presentation more common in primigravidas (first-time mothers) than multiparas (women who have given birth multiple times), in people who are sedentary, in premature labor, or in singleton pregnancies than multiple pregnancies?

Breech Presentation in Pregnancy: Risk Factors and Associations

Breech presentation is most common in premature labor compared to other scenarios presented in the question. 1, 2

Understanding Breech Presentation

Breech presentation refers to when a baby is positioned with its buttocks or feet toward the birth canal instead of the normal head-first (cephalic) position. The incidence of breech presentation varies significantly by gestational age:

• In extremely preterm births (24-27 weeks): 23.5% 2
• In term pregnancies (≥37 weeks): only 2.5% 2

This demonstrates a clear linear relationship between prematurity and breech presentation, with the incidence decreasing as gestational age advances.

Risk Factors for Breech Presentation

Prematurity

• The strongest association among the options presented is with prematurity 1, 2
• In premature labor, the fetus has not yet completed the normal rotation to cephalic presentation that typically occurs in the third trimester
• This is particularly evident in extremely preterm deliveries (before 28 weeks), where the majority of breech-presenting infants (88%) who present in labor deliver vaginally 3

Other Risk Factors (not the primary association)

1. Parity:

   • Nulliparity (first pregnancy) is associated with breech presentation, but primarily in moderate to late preterm (32-36 weeks) and term pregnancies 2
   • This contradicts the option suggesting breech is more common in primigravidas than multiparas across all gestational ages

2. Physical Activity:

   • No strong evidence supports that sedentary lifestyle is a primary risk factor for breech presentation
   • This factor is not highlighted in major guidelines or research on breech presentation

3. Multiple vs. Singleton Pregnancies:

   • While multiple pregnancies have higher rates of complications overall, the question specifically asks about comparative rates of breech presentation
   • The evidence doesn't support that breech is more common in singleton than multiple pregnancies

Clinical Implications

The high rate of breech presentation in preterm deliveries has important clinical implications:

• Vaginal delivery skills for breech-presenting infants remain essential for birth attendants, particularly for extremely preterm deliveries 3
• In preterm breech presentations, there are specific risk factors that differ from term breech presentations 2
• Preterm breech delivery is associated with higher risks of complications including low Apgar scores and potential birth injuries 4, 5

Conclusion

Among the options presented, the statement that breech presentation is more common in premature labor is the most accurate. The incidence of breech presentation decreases significantly as gestational age advances, from 23.5% in early preterm to only 2.5% at term, establishing prematurity as the strongest association with breech presentation among the choices given.