Neonatal Death and Morbidity in Vertex-Nonvertex Second Twins According to Mode of Delivery and Birth Weight
Abstract & Commentary
By John C. Hobbins, MD, Professor and Chief of Obstetrics, University of Colorado Health Sciences Center, Denver, is Associate Editor for OB/GYN Clinical Alert.
Dr. Hobbins reports no financial relationship to this field of study.
Synopsis: The risk of neonatal death and morbidity in second-born twins is higher in the group in which both twins were delivered vaginally and the group in which the second twin was delivered by cesarean delivery after the first twin was delivered vaginally compared with the group in which both twins were delivered by cesarean delivery.
Source: Yang Q, et al. Neonatal death and morbidity in vertex-nonvertex second twins according to mode of delivery and birth weight. Am J Obstet Gynecol. 2005;192:840-847.
I missed this article when it first emerged. however, during a recent perinatal conference in California, Dr. Michael Nageotte cited it in an excellent lecture on breeches. Since the report could have an impact in current practice, I am reviewing it in this issue.
Yang and colleagues combed through birth statistics data from 15,185 births in the United States between 1995-1997 in which a second twin presented as a nonvertex. Infants with birth weights of less than 1500 grams were excluded. Thirty-seven percent were delivered by Cesarean section empirically (group 1), while 15.5% had a Cesarean section for the second twin alone (group 2), and the remaining 46.8% had a vaginal delivery for both twins (group 3).
When comparing outcomes between group 1 and group 3, the second twins in group 3 had a higher rate of total neonatal death, asphyxia-related death, low Apgar scores (less than 7 at 5 minutes), and use of neonatal ventilation. When breaking down the results according to birth weight, the 500-1500 gram second twins had more total neonatal deaths, asphyxia-related deaths, lower Apgar scores, and ventilation use. There was no difference in neonatal injury. The heavier second twins, weighing 1500-4000 grams, had a higher rate of infant injury, low Apgar scores, ventilation use, and seizures, but no difference in neonatal death compared with those who were sectioned outright.
Yang et al concluded that their findings were "consistent with a prospective singleton term breech trial which found that planned Cesarean delivery was associated with reduced neonatal morbidity with planned vaginal birth."
Commentary
While sharpening our scalpels yet again for another reason to avoid vaginal delivery, it is important to look critically at the design and results of this study. When reviewing only birth certificates and CPT codes, there is no ability to determine, who, if anyone, was attending the deliveries, whether or not the second twin was alive before delivery (where vaginal delivery would have been indicated) or whether, in the mid 1990s, all the twins were known to be twins before delivery. Also, it is unknown in many cases if an external version was attempted (since there was a trend to do this at that time).
Something in this story is clearly missing since there was a greater incidence of birth injuries in infants weighing 1500 grams than in the very delicate premature breeches that have already been shown in singleton studies to do more poorly via the vaginal route, and, intuitively should be more vulnerable to manipulation.1-4
The Hannah et al RCT (a subject of a previous OB/GYN Clinical Alert), suggesting singleton breeches faired less well by the vaginal route, was quickly endorsed formally by the ACOG, essentially putting the nail in that coffin.1,5,6 It would be a shame if beech extraction of the second twin was completely abandoned since three randomized studies have shown no difference in outcome when the second nonvertex twin is delivered in this way, the last of which even showed a cost effective benefit in vaginal delivery.4
Unless new information surfaces, the available literature suggests that in experienced hands, and under the proper conditions, breech extraction should not be abandoned as an option for a second twin. The Yang study should not trump all of the other information out there.
References
- ACOG committee opinion: number 265, December 2001. Mode of term single breech delivery. Obstet Gynecol. 2001;98:1189-1190.
- Rabinovici J, et al. Randomized management of the second nonvertex twin: vaginal delivery or cesarean section. Am J Obstet Gynecol. 1987;156:52-56.
- Chauhan SP, et al. Delivery of the nonvertex second twin: breech extraction versus external cephalic version. Am J Obstet Gynecol. 1995;173:1015-1020.
- Mauldin JG, et al. Cost-effective delivery management of the vertex and nonvertex twin gestation. Am J Obstet Gynecol.1998;179:864-869.
- Hannah ME, et al. Planned caesarean section versus planned vaginal birth for breech presentation at term: a randomised multicentre trial. Term Breech Trial Collaborative Group. Lancet. 2000;356:1375-1383.
- Hobbins J. Is cesarean section safer for breeches than vaginal delivery? OB/GYN Clinical Alert. 2001;17:81-82.
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