Dutch study clarifies risk of attempted vaginal birth of breech fetus

Should a baby that presents breech at term be delivered vaginally or by cesarean delivery? In October 2000, results of the Term Breech Trial (TBT), the largest randomized controlled trial to investigate the effect of delivery mode for term breech deliveries on neonatal and maternal outcomes, essentially answered this question, showing that planned cesarean delivery was safer than planned vaginal delivery (with combined perinatal morbidity and mortality scores of 5% vs 16%, respectively).¹ These study results affected national guidelines for choosing delivery mode in the Netherlands as well as other countries around the world.

What has been the impact on mode of delivery and neonatal outcome in the Netherlands since the TBT’s publication? Furthermore, are there antepartum parameters that can distinguish which women are at high risk versus low risk for adverse neonatal outcomes when presenting breech at delivery? Vlemmix and colleagues sought to answer these questions, using retrospective data from the Netherlands Perinatal Registry (PRN) from 1999 through 2007.¹

Perinatal death decreased over time—but only for women electing cesarean
During the study period, approximately 4% of all births were breech. The researchers studied 58,320 women with term breech delivery, using the PRN. They noted an increase in the elective cesarean delivery (ECD) rate for these women, from 24% before October 2000 to 60% after December 2000, and as a consequence, found that overall perinatal mortality decreased from 1.3% to 0.7% (odds ratio [OR] 0.51; 95% confidence interval [CI] 0.28–0.93).¹

However, among the women who underwent planned vaginal delivery, the overall perinatal mortality remained stable (1.7% vs 1.6%; OR, 0.96; 95% CI, 0.52–1.76). “Despite the lower percentage of women opting for or offered a vaginal delivery, and despite a higher emergency cesarean rate during vaginal breech birth, neonatal outcome within the planned vaginal birth group did not improve,” state the authors.¹

Putting the results in absolute numbers
The investigators say that the 40% of Dutch women with breech presentation at term who still attempt vaginal birth do so without improved neonatal outcome; these deliveries generate a 10-fold higher fetal mortality rate compared with ECD. Further, no subgroup of women, when evaluating parity, onset of labor, type of breech presentation, and birthweight, could be identified with a low risk of poor neonatal outcome during planned vaginal delivery compared with ECD.¹

Since the TBT, 1,692 more combined elective and emergency cesarean deliveries were performed annually, leading to five less neonatal deaths per year (number needed to treat, 338). If all women who still undergo planned vaginal birth receive ECD, 6,490 more ECDs would be performed, with 10 less neonatal deaths, 116 less neonates with low Apgar score, and 20 less neonates with birth trauma per year, according to the researchers.¹

They suggest that clinicians use the results of this study when counseling women with a term breech presentation on mode of delivery. “To properly inform patients, a combination of risk presentation (absolute risks, relative risks and figures) is necessary to enable individual informed decision making.”¹

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