by Henci Goer
In order to offer evidence-based maternity care, we need to keep up with the current research. Unfortunately, some research studies are poorly designed or biased - even when published in respected peer-reviewed journals. Making matters worse, some of these flawed studies receive heavy publicity, including editorials and press releases that exaggerate and misrepresent their findings. Because of that publicity, these studies have resulted in rapid, widespread changes in practice.
This problem makes our job of promoting evidence-based care more difficult. We often encounter policies, practices, and protocols based on poor-quality or misinterpreted research, yet critically reviewing the evidence takes time and specialized knowledge.
The Lamaze Institute for Normal Birth has developed brief critiques of some influential studies that have shaped policy and practice. These critiques are meant to help childbirth professionals evaluate the quality of evidence on these important topics.
Breech Birth
Hannah, M. E., Hannah, W. J., Hewson, S. A., Hodnett, E. D., Saigal, S., & Willan, A. R. (2000). Planned caesarean section versus planned vaginal birth for breech presentation at term: A randomised multicentre trial. Term breech trial collaborative group. Lancet, 356(9239), 1375-1383.
Main conclusion: Planned cesarean section is safer than planned vaginal birth for the baby in a breech presentation. There are no differences in maternal outcomes between the two modes of birth. Read this critique.
Epidural Analgesia
Wong, C. A., et al. (2005). The risk of cesarean delivery with neuraxial analgesia given early versus late in labor. New England Journal of Medicine, 352 (7), 655-665.
Main conclusion: Early epidurals do not increase the cesarean rate compared with late epidurals. Read this critique.
Home Birth
Pang, J. W., et al. (2002). Outcomes of planned home births in Washington State: 1989-1996. Obstetrics & Gynecology, 100 (2), 253-259.
Main conclusion: Planned home birth is associated with an increased risk of newborn death compared with planned hospital birth. Read this critique.
Induction of Labor
Crowley P. Interventions for preventing or improving the outcome of delivery at or beyond term. (Cochrane Review). In: The Cochrane Library. Issue 2. 2004.
Main conclusion: Induction at 41 weeks gestation reduces the perinatal mortality rate without increasing the cesarean rate. Read this critique.
Hannah, M. E., et al. (1992). Induction of labor as compared with serial antenatal monitoring in post-term pregnancy. A randomized controlled trial. The Canadian Multicenter Post-term Pregnancy Trial Group. New England Journal of Medicine, 326 (24), 1587-1592.
Main conclusion: Induction after 41 weeks gestation reduces the cesarean rate. Read this critique.
Hannah, M. E., et al. (1996). Induction of labor compared with expectant management for prelabor rupture of the membranes at term. TermPROM study group. New England Journal of Medicine, 334(16), 1005-1010.
Main conclusion: Immediate induction with oxytocin following prelabor rupture of membranes (PROM) at term reduces the likelihood of infection without increasing the chance of cesarean section. Read this critique.
Nicholson, J. M., et al. (2007). A preventive approach to obstetric care in a rural hospital: Association between higher rates of preventive labor induction and lower rates of cesarean delivery. Annals of Family Medicine, 5(4), 310-319.
Main conclusion: Routine induction with PGE2 in women thought to be at risk of "cephalopelvic disproportion" or "uteroplacental insufficiency" reduces the cesarean section rate and is safe for babies. Read this critique.
Vaginal Birth After Cesarean (VBAC)
Landon, M. B., et al. (2004). Maternal and perinatal outcomes associated with a trial of labor after prior cesarean delivery. New England Journal of Medicine, 351 (25), 2581-2589.
Main conclusion: Planned VBAC is associated with greater perinatal risk than elective repeat cesarean. Read this critique.
Lieberman, E., et al. (2004). Results of the national study of vaginal birth after cesarean in birth centers. Obstetrics & Gynecology, 104 (5 Pt 1), 933-942.
Main conclusion: Despite a low uterine rupture rate and a high VBAC rate, birth centers should refer women desiring VBAC to hospitals on grounds that they are more likely to experience labor complications requiring hospital delivery. Read this critique.
Smith, G. C., et al. (2002). Risk of perinatal death associated with labor after previous cesarean delivery in uncomplicated term pregnancies. JAMA, 287 (20), 2684-2690.
Main conclusion: Planned VBAC increases the risk of perinatal death compared with planned repeat cesarean. Read this critique.
Lydon-Rochelle, M., et al. (2001). Risk of uterine rupture during labor among women with a prior cesarean delivery. New England Journal of Medicine, 345 (1), 3-8.
Main conclusion: Planned VBAC is associated with more uterine ruptures than elective repeat cesarean. Read this critique.
Mozurkewich, E. L., & Hutton, E. K. (2000). Elective repeat cesarean delivery versus trial of labor: a meta-analysis of the literature from 1989 to 1999. American Journal of Obstetrics & Gynecology, 183 (5), 1187-1197.
Main conclusion: Compared with elective repeat cesareans, planned VBAC may result in small increases in uterine rupture and perinatal mortality rates while decreasing maternal morbidity. Read this critique.
McMahon, M. J., et al. (1996). Comparison of a trial of labor with an elective second cesarean section. New England Journal of Medicine, 335 (10), 689-695.
Main conclusion: Major maternal complications occur nearly twice as often with VBAC as with elective repeat cesarean section. Read this critique.