Vaginal birth after caesarean

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Vaginal birth after caesarean
MeSH D016064

Vaginal birth after caesarean (VBAC) is the practice of birthing a baby vaginally after a previous baby has been delivered through caesarean section (surgically).[1] The American College of Obstetricians and Gynecologists (ACOG) explains that "at an individual level VBAC is associated with decreased maternal morbidity and a decreased risk of complications in future pregnancies. At a population level, VBAC also is associated with a decrease in the overall cesarean delivery rate." [2] According to the American Pregnancy Association, 90% of women who have undergone caesarean deliveries are candidates for VBAC.[3] Approximately 60-80% of women opting for VBAC will successfully give birth vaginally, which is comparable to the overall vaginal delivery rate in the United States in 2010.[3][4][5]

VBAC trends in the United States[edit]

Although caesarean sections made up only 5% of all deliveries in the early 1970s,[6] among women who did have primary caesarean sections, the century-old opinion held, "Once a caesarean, always a caesarean." Overall, cesarean sections became so commonplace that the cesarean delivery rate climbed to over 31% in 2006.[2] A mother-driven movement supporting VBAC changed standard medical practice, and rates of VBAC rose in the 1980s and early 1990s. However, a major turning point occurred in 1996 when one well publicized study in The New England Journal of Medicine reported that vaginal delivery after previous caesarean section resulted in more maternal complications than a repeat caesarean delivery.[7] The American College of Obstetrics and Gynecology subsequently issued guidelines which identified VBAC as a high-risk delivery requiring the availability of an anesthesiologist, an obstetrician, and an operating room on standby.[8] Logistical and legal (professional liability) concerns led many hospitals to enact overt or de facto VBAC bans. As a result, the rate at which VBAC was attempted fell from 26% in the early 1990s to 8.5% in 2006.[2][9]

In March 2010, the National Institutes of Health met to consolidate and discuss the overall up-to-date body of VBAC scientific data and concluded, "Given the available evidence, trial of labor is a reasonable option for many pregnant women with one prior low transverse uterine incision.".[10] Simultaneously, the U.S. Department of Health and Human Services Agency for Healthcare Research and Quality reported that VBAC is a reasonable and safe choice for the majority of women with prior caesarean and that there is emerging evidence of serious harms relating to multiple caesareans.[11] In July 2010, The American College of Obstetricians and Gynecologists (ACOG) similarly revised their own guidelines to be less restrictive of VBAC, stating, "Attempting a vaginal birth after cesarean (VBAC) is a safe and appropriate choice for most women who have had a prior cesarean delivery, including for some women who have had two previous cesareans."[12]

Enhanced access to VBAC has been recommended based on the most recent scientific data on the safety of VBAC as compared to repeat caesarean section, including the following recommendation emerging from the NIH VBAC conference panel in March 2010, "We recommend that hospitals, maternity care providers, health care and professional liability insurers, consumers, and policymakers collaborate on the development of integrated services that could mitigate or even eliminate current barriers to trial of labor."[10] The U.S Department of Health and Human Services' Healthy People 2020 initiative includes objectives to reduce the primary caesarean rate and to increase the VBAC rate by at least 10% each.[13]

Drawbacks and benefits[edit]

A caesarean section leaves a scar in the wall of the uterus which is considered weaker than the normal uterine wall. During labor in a subsequent pregnancy, there is a small risk of a ruptured uterus (0.47% chance among women having a trial of labor after cesarean section versus 0.03% among women scheduling repeat caesarean deliveries).[11] If a uterine rupture does occur, the risk of perinatal death is approximately 6%.[11] Mothers with a previous lower uterine segment cesarean are considered the best candidates, as that region of the uterus is under less physical stress during labor and delivery. Aside from uterine rupture risk, the drawbacks of VBAC are usually minor and identical to those of any vaginal delivery, including the risk of perineal tearing. Maternal morbidity, NICU admissions, length of hospital stay, and medical costs are typically reduced following a VBAC rather than a repeat caesarean delivery.

The risk of post-operative infection doubles if vaginal delivery is attempted but results in another caesarean.[3]

Repeat caesarean sections become increasingly complicated with each subsequent operation, as the probability of internal abdominal adhesions, bladder injuries, and abnormal placentation (placenta praevia or placenta accreta) increases dramatically, with placenta accreta reportedly affecting 50-67% of women having three or more caesarean sections. According to the United States Agency for Healthcare Research and Quality, "Abnormal placentation has been associated with both maternal and neonatal morbidity including need for antepartum hospitalization, preterm delivery, emergent caesarean delivery, hysterectomy, blood transfusion, surgical injury, intensive care unit (ICU) stay, and fetal and maternal death and may be life-threatening for mother and baby."[11]

The benefits of VBAC are associated with avoiding the risks of major abdominal surgery. Compared to women who have elective repeat cesarean deliveries, women who undergo VBAC, have smaller risks of hemorrhage and infection and have faster recovery times.[2]


Eligibility to pursue a VBAC varies widely by provider and birth setting (hospital, birthing center, or home). Some commonly employed criteria include:[4]

  • If the previous caesarean(s) involved a low transverse incision there is less risk of uterine rupture than if there was a low vertical incision, classical incision, T-shaped, inverted T-shaped, or J-shaped incision.
  • A previous successful vaginal delivery (before or after the caesarean section) increases the chances of a successful VBAC.
  • The reason for the previous caesarean section should not be present in the current pregnancy.
  • The more caesarean sections that a woman has had, the less likely she will be eligible for VBAC.
  • The presence of twins will decrease the likelihood of VBAC. Some doctors will still allow VBAC if the twins are positioned properly for birth.
  • VBAC may be discouraged if there are other medical complications (such as diabetes), if the mother is over 40, if the pregnancy is post due date, or if the baby is malpositioned.

Some contraindications of a VBAC include:[14]

  • Maternal request for elective repeat CS after counselling
  • Maternal or fetal reasons to avoid vaginal birth in current pregnancy
  • Previous uterine incision other than transverse segment including classical
  • Previous complicated lower uterine segment transverse incision
  • Unknown previous uterine incision
  • VBAC after two or more prior lower uterine segment transverse CS is controversial
  • Previous uterine rupture
  • Previous hysterotomy or myomectomy entering the uterine cavity

According to ACOG guidelines, the following criteria may reduce the likelihood of VBAC success but should NOT preclude a trial of labor: having two prior caesarean sections, suspected fetal macrosomia (fetus greater than 4000-4500 grams in weight), gestation beyond 40 weeks, twin gestation, and previous low vertical or unknown previous incision type, provided a classical incision is not suspected.[15]

Depending on the provider, special precautions may be encouraged during a trial of labor following a caesarean section, including IV or IV port placement, continuous or intermittent fetal monitoring, and conservative or absent labor induction and augmentation using chemical stimulants. Other intrapartum management options, including analgesia/anesthesia, are identical to those of any labor and vaginal delivery.[16]


ACOG recommends that obstetricians offer most women with one prior cesarean section with a low-transverse incision a trial of labor (TOLAC) and that obstetricians should discuss the risks and benefits of VBAC with these patients.[2]

This VBAC success calculator is a useful educational tool (noted by the US Agency for Healthcare Research and Quality) for clinicians who are discussing the risks and benefits of VBAC with their patients.[17]

See also[edit]


  1. ^ Vaginal Birth After Cesarean (VBAC) - Overview, WebMD
  2. ^ a b c d e American College of Obstetricians and, Gynecologists (Aug 2010). "ACOG Practice bulletin no. 115: Vaginal birth after previous cesarean delivery.". Obstetrics and gynecology 116 (2 Pt 1): 450–63. doi:10.1097/AOG.0b013e3181eeb251. PMID 20664418. 
  3. ^ a b c "Vaginal Birth after Cesarean (VBAC)". American Pregnancy Association. Retrieved 2012-06-16. 
  4. ^ a b Vaginal birth after C-section (VBAC) guide, Mayo Clinic
  5. ^ "NCHS Data Brief: Recent Trends in Cesarean Delivery in the United States Products". Centers for Disease Control and Prevention. March 2010. Retrieved 2012-06-16. 
  6. ^ "Rates of Cesarean Delivery - United States, 1993". Centers for Disease Control and Prevention. Retrieved 2012-06-16. 
  7. ^ McMahon MJ, Luther ER, Bowes WA, Olshan AF (September 1996). "Comparison of a trial of labor with an elective second cesarean section". New England Journal of Medicine 335 (10): 689–95. doi:10.1056/NEJM199609053351001. PMID 8703167. Retrieved 2012-06-16. 
  8. ^ Int J Gyn Obs; 1999; vol 66, p. 197
  9. ^ "Cesarean births, repeat (percent)". Health Indicators Warehouse. Retrieved 2012-06-16. 
  10. ^ a b "NIH Vaginal Birth After Cesarean (VBAC) Conference - Panel Statement". NIH Consensus Development Program. March 8–10, 2010. Retrieved 2012-06-16. 
  11. ^ a b c d "Vaginal Birth After Cesarean: New Insights". Agency for Healthcare Research and Quality. March 2010. Retrieved 2012-06-16. 
  12. ^ [1]
  13. ^ "2020 Topics & Objectives: Maternal, Infant, and Child Health". U.S. Department of Health and Human Services. Retrieved 2012-06-16. 
  14. ^ Queensland Maternity and Neonatal Clinical Guidelines Program (November 2009). Queensland Maternity and Neonatal Clinical Guideline: Vaginal birth after caesarean section (VBAC). Retrieved 22 September 2012. 
  15. ^ ACOG Practice Bulletin Number 115, August 2010
  16. ^ "Guideline Synthesis: Vaginal Birth After Cesarean (VBAC)". National Guideline Clearinghouse. Retrieved 2012-06-16. 
  17. ^  Missing or empty |title= (help)

External links[edit]