A study conducted in Australia provides new data on the outcomes for mother and baby associated with either planned vaginal birth, or elective repeat caesarean section following a previous caesarean section.
Uncertainty exists about benefits and harms of a planned vaginal birth after caesarean (VBAC) compared with elective repeat caesarean (ERC). We conducted a prospective restricted cohort study consisting of a patient preference cohort study, and a small nested randomised trial to compare benefits and risks of a planned ERC with planned VBAC.
Methods and findings
2,345 women with one prior caesarean, eligible for VBAC at term, were recruited from 14 Australian maternity hospitals. Women were assigned by patient preference (n = 2,323) or randomisation (n = 22) to planned VBAC (1,225 patient preference, 12 randomised) or planned ERC (1,098 patient preference, ten randomised). The primary outcome was risk of fetal death or death of liveborn infant before discharge or serious infant outcome. Data were analysed for the 2,345 women (100%) and infants enrolled.
The risk of fetal death or liveborn infant death prior to discharge or serious infant outcome was significantly lower for infants born in the planned ERC group compared with infants in the planned VBAC group (0.9% versus 2.4%; relative risk [RR] 0.39; 95% CI 0.19–0.80; number needed to treat to benefit 66; 95% CI 40–200). Fewer women in the planned ERC group compared with women in the planned VBAC had a major haemorrhage (blood loss ≥1,500 ml and/or blood transfusion), (0.8% [9/1,108] versus 2.3% [29/1,237]; RR 0.37; 95% CI 0.17–0.80).
Among women with one prior caesarean, planned ERC compared with planned VBAC was associated with a lower risk of fetal and infant death or serious infant outcome. The risk of major maternal haemorrhage was reduced with no increase in maternal or perinatal complications to time of hospital discharge. Women, clinicians, and policy makers can use this information to develop health advice and make decisions about care for women who have had a previous caesarean.
Current Controlled Trials ISRCTN53974531
Please see later in the article for the Editors' Summary
Rates of caesarean section are rising around the world, particularly in high- and middle-income countries, where most women have a choice of how their baby is delivered. Historically, the obstetrician in charge of the woman's care made the decision on whether to perform an elective (planned) caesarean section based on medical criteria. For women who have had a previous caesarean section, typically, their options for mode of childbirth are either a trial of vaginal birth or an elective repeat caesarean section. The proportion of women attempting a vaginal birth after a previous caesarean section has been declining in many countries partly due to the variable chance of achieving a successful vaginal birth (reported between 56% and 80%) and partly because of negative reports of the risk of complications, both to the mother and the baby, of a having a vaginal delivery following a caesarean section. Consequently, the rates of repeat caesarean section have risen sharply, for example, currently 83% in Australia and almost 90% in the US.
Why Was This Study Done?
Both elective repeat caesarean section and subsequent vaginal delivery after a previous caesarean section have clinical risks and benefits. Most obviously, having a surgical procedure puts the woman having the repeat caesarean section at risk of surgical complications, especially if performed under a general anesthetic, and her baby may be at risk of respiratory complications. However, subsequent vaginal delivery following a previous caesarean section may put the mother at risk of bleeding severely enough to need a blood transfusion (more than 1,500 ml blood loss) and she may also be at increased risk of rupturing her uterus; and her baby may have an increased risk of dying or of becoming brain damaged due to lack of oxygen.
However, to date there have been no randomized controlled trials of elective repeat caesarean section versus vaginal delivery following a previous caesarean section to compare the health outcomes of mother and baby and a recent systematic review could draw no conclusions. So the researchers conducted this prospective cohort study based on patient preference (with a few women agreeing to be randomized to mode of delivery), to compare the health outcomes for mother and baby for elective repeat caesarean section versus vaginal delivery in women following a previous caesarean section.
What Did the Researchers Do and Find?
Between 2002 and 2007, the researchers recruited 2,345 suitable women (that is, women who had one previous caesarean section, were currently 37 weeks pregnant with a single baby, and who were clinically able to have a vaginal delivery) from 14 maternity hospitals throughout Australia. A few women (22) agreed to be randomized to either mode of delivery but most women chose her preferred option. Then, depending on the woman's preferences for mode of birth, participating obstetricians either scheduled a date for an elective caesarean section (1,098 women) or assessed on-going suitability for the woman to have a planned vaginal delivery (1,225 women). However only 535 (43.2%) women who chose to have a vaginal birth were able to deliver this way because of failure to progress in labor or fetal distress: 334 of these women (27.0%) had to have an elective caesarean section and 368 women had to have an emergency caesarean section.
Although no women died, women who had a planned caesarean section experienced less severe bleeding than women who delivered vaginally. There were no infant deaths in those born by elective caesarean section but two unexplained stillbirths in the planned vaginal delivery group. There was also a reduced risk of nonfatal serious outcome before discharge from hospital for infants delivered by in the elective caesarean section. The researchers calculated that one infant death or near death would be prevented for every 66 elective caesarean sections performed in women who had a previous caesarean section.
What Do These Findings Mean?
These findings show that in women who had delivered by a previous caesarean section delivering their next baby by planned caesarean section was associated with less infant death and better health outcomes for the mother before she was discharged from the hospital compared to women who had a subsequent vaginal delivery. This information can be used by women, clinicians, and policy makers in helping to make decisions about the mode of subsequent deliveries and best care for women who have had a previous caesarean section.
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001192.
This study is linked to a PLoS Medicine
Research Article by Fitzpatrick and colleagues and a PLoS Medicine
Perspective by Catherine Spong
The American Congress of Obstetricians and Gynecologists has information sheets for patients on caesarean sections and on vaginal birth after caesarean delivery
Childbirth Connection, a US-based not-for-profit organization, provides information about caesarean sections and about vaginal birth after caesarean
The National Childbirth Trust, a UK charity, provides information for parents on all aspects of pregnancy and birth, including caesarean sections and vaginal birth after caesarean delivery
The UK charity Healthtalkonline has personal stories from women making decisions about birth after a caesarean section