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Research and Evidence
Childbirth Connection

NOTE: For guiding decisions about care, Childbirth Connection gives priority to systematic reviews. These rigorous summaries of best available studies are the most trustworthy way to know the benefits and harms of specific practices.

There are pros and cons of planning a repeat cesarean and planning a vaginal birth after cesarean. This page provides you with the best available evidence about these two options for pregnant women with a past cesarean, as known from the most recent major evidence report (Guise et al, 2010) and other systematic reviews published since 2005. Below we also summarize many differences in outcomes between cesarean and vaginal birth that likely apply to women and babies after a previous cesarean, but have not been studied specifically in this population.

We strongly encourage you to read the Maternity Care section for more information about maternity care decision-making and the importance of considering high-quality evidence.

What does the research say about VBAC compared to repeat C-section?

If you do not have a clear and compelling need for a cesarean in your present pregnancy, having a VBAC rather than a repeat C-section is likely to be:

  • Safer for you in this pregnancy
  • Much safer for you and your babies in any future pregnancies

When thinking about the health and safety of your baby in your current pregnancy, there are trade-offs to consider: VBAC has some advantages, and a repeat C-section has others. Despite limitations of the best available research, the following conclusions seem clear:

  • The scar is more likely to give way during a VBAC labor than in a repeat C-section, but this risk is low. A uterine rupture will occur about once in every 238 labors after C-section.Guise, J.M., Eden, K., Emeis, C., . . . McDonagh, M. (2010). Vaginal birth after cesarean: New insights. Evidence Report/Technology Assessment No.191. (Prepared by the Oregon Health & Science University Evidence-based Practice Center under Contract No. 290-2007-10057-I). AHRQ Publication No. 10-E003. Rockville, MD: Agency for Healthcare Research and Quality. (When this happens, a C-section is done right away.)
  • The added risk that the baby will die from a problem with the scar during a VBAC labor compared with a repeat cesarean is very low. A baby will die due to uterine rupture about once in 5,200 labors after C-section.Guise, J.M., Eden, K., Emeis, C., . . . McDonagh, M. (2010). Vaginal birth after cesarean: New insights. Evidence Report/Technology Assessment No.191. (Prepared by the Oregon Health & Science University Evidence-based Practice Center under Contract No. 290-2007-10057-I). AHRQ Publication No. 10-E003. Rockville, MD: Agency for Healthcare Research and Quality.
  • If the scar gives way, some women require an urgent hysterectomy (removal of the uterus). However, C-sections also increase risk for urgent hysterectomy, and women who plan a VBAC are not more likely to experience an unplanned hysterectomy than women who plan a repeat C-section.Guise, J.M., Eden, K., Emeis, C., . . . McDonagh, M. (2010). Vaginal birth after cesarean: New insights. Evidence Report/Technology Assessment No.191. (Prepared by the Oregon Health & Science University Evidence-based Practice Center under Contract No. 290-2007-10057-I). AHRQ Publication No. 10-E003. Rockville, MD: Agency for Healthcare Research and Quality.

The following factors do not increase risk of the scar giving way during labor (we talk more about these factors here):

  • Unknown type of uterine scar
  • A low up-and-down (vertical) cut in the uterus was used for the previous C-section
  • The baby might be quite large (weigh more than 8 pounds, 13 ounces)
  • Pregnancy goes past 40 weeks, and labor is not inducedGuise, J.M., Eden, K., Emeis, C., . . . McDonagh, M. (2010). Vaginal birth after cesarean: New insights. Evidence Report/Technology Assessment No.191. (Prepared by the Oregon Health & Science University Evidence-based Practice Center under Contract No. 290-2007-10057-I). AHRQ Publication No. 10-E003. Rockville, MD: Agency for Healthcare Research and Quality.

What problems are more common with repeat C-section?

Systematic reviews have found that repeat cesarean is worse than planned VBAC, for

  • Physical problems for mothers. Compared with vaginal birth, C-section increases a woman’s risk for a number of physical problems, ranging from less common but potentially life-threatening problems like hemorrhage (severe bleeding), blood clots and bowel obstruction (due to scarring and adhesions from the surgery) to much more common problems like longer-lasting and more severe pain and infection. Scarring and adhesion tissue can make it more likely that women will have ongoing pelvic pain and twisted bowel.Guise, J.M., Eden, K., Emeis, C., . . . McDonagh, M. (2010). Vaginal birth after cesarean: New insights. Evidence Report/Technology Assessment No.191. (Prepared by the Oregon Health & Science University Evidence-based Practice Center under Contract No. 290-2007-10057-I). AHRQ Publication No. 10-E003. Rockville, MD: Agency for Healthcare Research and Quality.
  • Longer hospital stays. If a woman has a C-section, she is more likely to stay in the hospital longer and to be re-hospitalized.Guise, J.M., Eden, K., Emeis, C., . . . McDonagh, M. (2010). Vaginal birth after cesarean: New insights. Evidence Report/Technology Assessment No.191. (Prepared by the Oregon Health & Science University Evidence-based Practice Center under Contract No. 290-2007-10057-I). AHRQ Publication No. 10-E003. Rockville, MD: Agency for Healthcare Research and Quality.

As the number of cesareans (and related scarring and adhesions) grow, risks for women and babies grow. A systematic reviewMarshall, N., Fu, R., & Guise, J. (2011). Impact of multiple cesarean deliveries on maternal morbidity: A systematic review. American Journal of Obstetrics and Gynecology, 205(3), e1-8. found that risk of the following complications associated with cesarean increases with each additional cesarean:

  • Measures of serious maternal health problems (severe morbidity)
  • Emergency surgery to remove the uterus (hysterectomy)
  • Serious condition of the placenta covering the opening of the cervix (placenta previa)Guise, J.M., Eden, K., Emeis, C., . . . McDonagh, M. (2010). Vaginal birth after cesarean: New insights. Evidence Report/Technology Assessment No.191. (Prepared by the Oregon Health & Science University Evidence-based Practice Center under Contract No. 290-2007-10057-I). AHRQ Publication No. 10-E003. Rockville, MD: Agency for Healthcare Research and Quality.
  • Serious condition of the placenta growing into the wall of the uterus (placenta accreta)Guise, J.M., Eden, K., Emeis, C., . . . McDonagh, M. (2010). Vaginal birth after cesarean: New insights. Evidence Report/Technology Assessment No.191. (Prepared by the Oregon Health & Science University Evidence-based Practice Center under Contract No. 290-2007-10057-I). AHRQ Publication No. 10-E003. Rockville, MD: Agency for Healthcare Research and Quality.
  • Excessive blood loss (hemorrhage)
  • Blood given through IV line (blood transfusion)
  • Scars that cause organs to bind together and may lead to pain and other problems (adhesions)
  • Surgical injury

What problems are more common with C-section as compared to vaginal birth (but have not been sorted out for women giving birth after previous cesarean)?

Short-term maternal problems. Systematic reviews have found that cesarean is worse than vaginal birth for women (but have not been specifically sorted out for women with a past cesarean):

  • Impaired physical health for at least the first two months after birthVan der Woude, D.A., Pijnenborg, J.M., & de Vries, J. (2015). Health status and quality of life in postpartum women: A systematic review of associated factors. European Journal of Obstetrics & Gynecology and Reproductive Biology, 185, 45-52.
  • Not establishing breastfeeding, which benefits both women and babies; this especially occurs when cesareans are scheduled before laborPrior, E., Santhakumaran, S., Gale, C., Philipps, L.H., Modi, N., Hyde, M.J. (2012). Breastfeeding after cesarean delivery: a systematic review and meta-analysis of world literature. American Journal of Clinical Nutrition, 95,1113-35

Maternal problems that only happen with cesarean birth. The following would not occur with vaginal birth:

  • Mistaken surgical cut (for example, a nicked bladder) to the mother
  • Opening the wound to take care of a problem
  • Severe and/or long-term pain at the site of the cesarean cut
  • Infection introduced through the surgical cuts
  • A pregnancy that grows in a previous scar (cesarean ectopic pregnancy)
  • A placenta that implants in a previous scar (placenta accreta)
  • Internal scar tissue (dense adhesions) that make future surgeries more difficult and can cause more complications

Short- and longer-term problems for the baby. Systematic reviews have found that cesarean is worse than vaginal birth for babies (but have not been specifically sorted out for babies of women with a past cesarean):

  • Not establishing breastfeeding, which especially occurs when cesareans are scheduled before laborPrior, E., Santhakumaran, S., Gale, C., Philipps, L.H., Modi, N., Hyde, M.J. (2012). Breastfeeding after cesarean delivery: a systematic review and meta-analysis of world literature. American Journal of Clinical Nutrition, 95,1113-35
  • Increased risk of breathing problemsHansen, A.K., Wisborg, K., Uldjerg, N., & Henriksen, T.B. (2007). Elective caesarean section and respiratory morbidity in the term and near-term neonate. Acta Obstet Gynecol Scan, 86,389-94.
  • Less blood flowing from the placenta at birth and less ironZhou, Y., Li, H., Zhu, L., & Liu, J. (2014). Impact of cesarean section on placental transfusion and iron-related hematological indices in term neonates: A systematic review and meta-analysis. Placenta, 35, 1-8.
  • Likelihood of developing series of chronic diseases in childhood:
    • Childhood-onset (Type 1) diabetesCardwell, C., Stene, L., G, J., Cinek, O., Svensson, J., Goldacre, M., . . . Patterson, C. (2008). Caesarean section is associated with an increased risk of childhood-onset type 1 diabetes mellitus: A meta-analysis of observational studies. Diabetologia, 51(5), 726-35
    • Childhood obesity,Kuhle, S., Tong, O., & Woolcott, C. (2015). Association between caesarean section and childhood obesity: A systematic review and meta-analysis. Obesity Reviews, 16, 295-303. obesity in adulthoodDarmasseelane, K., Hyde, M., Santhakumaran, S., Gale, C., & Modi, N. (2014). Mode of Delivery and Offspring Body Mass Index, Overweight and Obesity in Adult Life: A Systematic Review and Meta-Analysis. PLoS One, 9, e97827. or bothLi, H., Zhou, Y., & Liu, J. (2013). The Impact of Cesarean Section on Offspring Overweight and Obesity. Obstetrical & Gynecological Survey, 37, 9-11.
    • Autism spectrum disorderCurran, E., O’Neill, S., Cryan, J., Kenny, L., Dinan, T., Khashan, A., & Kearney, P. (2014). Research Review: Birth by caesarean section and development of autism spectrum disorder and attention-deficit/hyperactivity disorder: A systematic review and meta-analysis. Journal of Child Psychology and Psychiatry, 56, 500-508.
    • Chronic inflammatory bowel disease with abdominal pain, diarrhea, weight loss, anemia and fatigue (Crohn’s disease)Li, Y., Tian, Y., Zhu, W., Gong, J., Gu, L., Zhang, W, & Li, J. (2014). Cesarean delivery and risk of inflammatory bowel disease: A systematic review and meta-analysis. Scandinavian Journal of Gastroenterology, 49(7), 834-844.
    • AsthmaThavagnanam, S., Fleming, J., Bromley, A., Shields, M., & Cardwell, C. (2008). A meta-analysis of the association between Caesarean section and childhood asthma. Clinical & Experimental Allergy, 38, 629-633. AND Bager, P., Wohlfahrt, J., & Westergaard, T. (2008). Caesarean delivery and risk of atopy and allergic disease: Meta-analyses. Clinical & Experimental Allergy, 38(4), 634-642.
    • Food sensitivities and allergiesKoplin, J., Allen, K., Gurrin, L., Osborne, N., Tang, M., & Dharmage, S. (2008). Is caesarean delivery associated with sensitization to food allergens and IgE-mediated food allergy: A systematic review. Pediatric Allergy and Immunology, 19, 682-687.
    • Hay feverBager, P., Wohlfahrt, J., & Westergaard, T. (2008). Caesarean delivery and risk of atopy and allergic disease: Meta-analyses. Clinical & Experimental Allergy, 38(4), 634-642.

Newborn problem that only happens with cesarean birth. A mistaken surgical cut to the baby would not occur with vaginal birth

Problems in future pregnancies. Systematic reviews have found that women with pregnancies after previous cesarean birth are more likely than those with previous vaginal birth (but have not sorted out differences in mode of birth after cesarean birth) to experience:

  • Splitting open of the uterus (uterine rupture)Hofmeyr, G.J., Say, L., & Gülmezoglu, A.M. (2005). WHO systematic review of maternal mortality and morbidity: The prevalence of uterine rupture. BJOG, 112(9), 1221-1228.
  • Emergency surgery to remove the uterus (hysterectomy)Rossi, A., Lee, R., & Chmait, R. (2010). Emergency Postpartum Hysterectomy for Uncontrolled Postpartum Bleeding: A Systematic Review. Obstetrics & Gynecology, 115(3),1453-1454. AND de la Cruz, C., Thompson, E., O’Rourke, K., & Nembhard, W. (2015). Cesarean section and the risk of emergency peripartum hysterectomy in high-income countries: A systematic review. Archives of Gynecology and Obstetrics, 292(6), 1201-15
  • Serious condition of the placenta covering the opening of the cervix (placenta previa)Gurol-Urganci, I., Cromwell, D., Edozien, L., Smith, G., Onwere, C., Mahmood, T., & Meulen, J. (2011). Risk of placenta previa in second birth after first birth cesarean section: A population-based study and meta-analysis. BMC Pregnancy and Childbirth, 11, 95. AND Klar, M., & Michels, K.B. (2014). Cesarean section and placental disorders in subsequent pregnancies: A meta-analysis. Journal of Perinatal Medicine, 42(5), 871-883.
  • Serious condition of the placenta growing into the wall of the uterus (placenta accreta)Klar, M., & Michels, K.B. (2014). Cesarean section and placental disorders in subsequent pregnancies: A meta-analysis. Journal of Perinatal Medicine, 42(5), 871-883.
  • Serious condition of the placenta separating from the wall of the uterus before the birth (placental abruption)Klar, M., & Michels, K.B. (2014). Cesarean section and placental disorders in subsequent pregnancies: A meta-analysis. Journal of Perinatal Medicine, 42(5), 871-883. AND Guise, J.M., Eden, K., Emeis, C., . . . McDonagh, M. (2010). Vaginal birth after cesarean: New insights. Evidence Report/Technology Assessment No.191. (Prepared by the Oregon Health & Science University Evidence-based Practice Center under Contract No. 290-2007-10057-I). AHRQ Publication No. 10-E003. Rockville, MD: Agency for Healthcare Research and Quality.
  • A stillborn babyMoraitis, A.A., Oliver-Williams, C., Wood, A.M., Fleming, M., Pell, J.P., & Smith, G.C.S. (2015). Previous caesarean delivery and the risk of unexplained stillbirth: retrospective cohort study and meta-analysis. BJOG: An International Journal of Obstetrics & Gynaecology 122(11), 1467-1474. AND O’Neill, S., Kearney, P., Kenny, L., Khashan, A., Henriksen, T., Lutomski, J., & Greene, R. (2013). Caesarean Delivery and Subsequent Stillbirth or Miscarriage: Systematic Review and Meta-Analysis. PLoS One, 8(1), e54588.

Longer-term problems for women. Systematic reviews have found that women who have given birth by cesarean versus vaginal birth (but have not sorted differences by mode of birth after cesarean) are more likely than those with vaginal births to experience in the future:

  • Difficulty becoming pregnant, leading to a lower pregnancy rateGurol-Urganci, I., Bou-Antoun, S., Lim, C., Cromwell, D., Mahmood, T., Templeton, A., & Meulen, J. (2013). Impact of Caesarean section on subsequent fertility: A systematic review and meta-analysis. Human Reproduction, 28(7), 1943-1952.
  • Difficulty remaining pregnant, leading to a lower birth rateGurol-Urganci, I., Bou-Antoun, S., Lim, C., Cromwell, D., Mahmood, T., Templeton, A., & Meulen, J. (2013). Impact of Caesarean section on subsequent fertility: A systematic review and meta-analysis. Human Reproduction, 28(7), 1943-1952.
  • A desire to wait longer before becoming pregnant againO’Neill, S., Kearney, P., Kenny, L., Khashan, A., Henriksen, T., Lutomski, J., & Greene, R. (2013). Caesarean Delivery and Subsequent Stillbirth or Miscarriage: Systematic Review and Meta-Analysis. PLoS One, 8(1), e54588.
  • Ongoing pain in the pelvis areaLatthe, P., Mignini, L., Gray, R., Hills, R., & Khan, K. (2006). Factors predisposing women to chronic pelvic pain: a systematic review. BMJ,332, 749-55.

What problems are more common with vaginal birth as compared to C-section (but have not been sorted out for women giving birth after previous cesarean)?

C-section offers advantages in a few areas, primarily with some aspects of the recovery period after birth. Some practices used with vaginal birth, such as episiotomy, are associated with pelvic floor problems, but it’s wrong to conclude that vaginal birth itself causes such problems (research is needed to better understand the role of care practices in pelvic floor outcomes) (see the section Preventing Pelvic Floor Dysfunction for more information on this issue).

  • A woman who has a vaginal birth is more likely to:
    • Have a painful vaginal area in the weeks after birth
    • Leak urine with stress, such as vigorous exercise, short-term after birth (urinary stress incontinence)Press, J.Z., Klein, M.C., Kaczorowski, J., Liston, R.M., von Dadelszen, P. (2007). Does cesarean section reduce postpartum urinary incontinence? A systematic review. Birth, 34(3), 228-237.
  • Babies born vaginally have been shown to be at higher risk for a nerve injury affecting the shoulder, arm or hand (brachial plexus injury). It is usually temporary

A systematic review has found that having a cesarean versus vaginal birth does not protect against having uncontrolled loss of feces or gas (anal incontinence).Nelson, R.L., Furner, S.E., Westercamp, M., & Farquhar, C. (2010). Cesarean delivery for the prevention of anal incontinence. Cochrane Database of Systematic Reviews, (2):CD006756.

A systematic review has found that having a cesarean versus vaginal birth does not protect against severe urinary stress incontinence and any urinary urge incontinence (difficulty waiting to urinate).Press, J.Z., Klein, M.C., Kaczorowski, J., Liston, R.M., von Dadelszen, P. (2007). Does cesarean section reduce postpartum urinary incontinence? A systematic review. Birth, 34(3), 228-237.

Maternal problems that only happen with vaginal birth. The following would not occur with cesarean birth:

  • Injury to the vulva or vagina, with possible pain and infection (genital trauma)
  • A tear or intentional cut (episiotomy) from the opening of the vagina toward the anus, with possible pain and infection (perineal trauma)

How does a planned C-section differ from an unplanned C-section?

A planned C-section offers some advantages over an unplanned C-section that occurs during labor. For example, there is a lower risk of surgical injuries and of infections. Nonetheless, a planned cesarean still involves the risks associated with major surgery. And both planned and unplanned cesareans result in a uterine scar, which increases risk for serious concerns for mothers and babies in future pregnancies, and for adhesion-relation problems in mothers at any time. There are growing concerns that shortening pregnancy (with a planned cesarean or induced labor) cuts off many important preparations for safe, healthy birth that take place in women and fetuses at the end of pregnancy.

What could increase my risk of having problems with my C-section scar?

If you decide to plan for a VBAC, it’s a good idea to choose a hospital capable of handling an urgent C-section at any time (it must have someone who can perform the surgery, an anesthesiologist and a pediatrician immediately available around-the-clock and a blood bank open 24/7). If these resources are not available in your hospital, you might want to consider another setting where they are available.

Are there any situations where the risk of the scar rupturing is so high I shouldn’t try for VBAC?

Almost all care providers, including those who usually encourage VBAC, would strongly recommend planned cesarean in the following situations because, on average, the scar will rupture in 8 to 12 out of every 100 women:

  • Your uterine scar is not side-to-side (low transverse scar), because it may be weaker. It could be a vertical (classical) scar or an upside-down T- or J-shaped scar.
  • You have had previous uterine surgery for gynecologic problems, like removing fibroids.
  • Your uterine scar opened and caused problems in a previous labor. The fact that it caused problems before is the important part; often scar openings are small and harmless and don’t indicate future problems.

Are there any situations where the risk of the scar rupturing is lower than average?

If you have ever given birth vaginally or had a VBAC, your chance of having scar problems with a VBAC labor are reduced.Guise, J.M., Eden, K., Emeis, C., . . . McDonagh, M. (2010). Vaginal birth after cesarean: New insights. Evidence Report/Technology Assessment No.191. (Prepared by the Oregon Health & Science University Evidence-based Practice Center under Contract No. 290-2007-10057-I). AHRQ Publication No. 10-E003. Rockville, MD: Agency for Healthcare Research and Quality.

Does starting labor artificially (induction) affect the likelihood of scar rupture?

The research findings here are mixed. The most recent major evidence report on this topic concluded that there is probably an increased risk of uterine rupture when labor is induced after 40 weeks, but not when labor is induced prior to 40 weeks.Guise, J.M., Eden, K., Emeis, C., . . . McDonagh, M. (2010). Vaginal birth after cesarean: New insights. Evidence Report/Technology Assessment No.191. (Prepared by the Oregon Health & Science University Evidence-based Practice Center under Contract No. 290-2007-10057-I). AHRQ Publication No. 10-E003. Rockville, MD: Agency for Healthcare Research and Quality.

The risk may depend on the methods used to induce labor. Medical agents used to soften and shorten the cervix (the opening to the uterus) may increase the likelihood that the scar will open and lead to problems in labor. Some researchers think these agents may soften (and thus weaken) the uterine scar as well. These agents belong to a family of hormone-like substances called prostaglandins and include Cytotec, Cervidil and Prepidil. Cytotec (also known as misoprostol) appears to be the riskiest option and experts agree it should not be used in VBAC labors. Use of a Foley catheter, a mechanical method to soften and open the cervix, does not appear to be any riskier than medical agents, but more research is needed.Guise, J.M., Eden, K., Emeis, C., . . . McDonagh, M. (2010). Vaginal birth after cesarean: New insights. Evidence Report/Technology Assessment No.191. (Prepared by the Oregon Health & Science University Evidence-based Practice Center under Contract No. 290-2007-10057-I). AHRQ Publication No. 10-E003. Rockville, MD: Agency for Healthcare Research and Quality.

Using synthetic oxytocin (Pitocin or “Pit”) by itself to try to start (induce) labor may also increase the likelihood that the scar will give way, but oxytocin appears to be safer than prostaglandins. Giving oxytocin in labor to strengthen contractions (labor augmentation or stimulation) may also increase the risk of scar problems.Guise, J.M., Eden, K., Emeis, C., . . . McDonagh, M. (2010). Vaginal birth after cesarean: New insights. Evidence Report/Technology Assessment No.191. (Prepared by the Oregon Health & Science University Evidence-based Practice Center under Contract No. 290-2007-10057-I). AHRQ Publication No. 10-E003. Rockville, MD: Agency for Healthcare Research and Quality.

Visit the Labor Induction section to learn more about this topic.

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