VBAC Calculator
Assess your candidacy for Vaginal Birth After Cesarean.
This is an Informational Guide, Not a Predictive Calculator
Positive Factors (Increase VBAC Success)
Contraindications (Usually Prevent VBAC Attempt)
For women who have previously had a Cesarean delivery (C-section), a subsequent pregnancy brings up an important question: "Can I have a vaginal birth this time?" The answer is often yes. A Vaginal Birth After Cesarean, or VBAC, is a safe and viable option for many women. The process of laboring for a VBAC is called a Trial of Labor After Cesarean (TOLAC). This guide is designed to explain the benefits, risks, and the key factors that help you and your healthcare provider decide if a TOLAC is a good choice for you.
This is an educational guide, not a predictive tool. The decision to pursue a VBAC is highly individual and must be made in close consultation with your obstetrician or midwife, who can assess your specific medical history and circumstances.
Why Consider a VBAC? The Benefits
Choosing to attempt a VBAC can have several advantages over a scheduled repeat C-section:
- Avoids Major Abdominal Surgery: A VBAC allows you to avoid the risks associated with another surgery, such as infection, blood loss, and longer recovery times.
- Shorter Recovery Period: Recovery from a vaginal birth is typically faster and less painful than recovery from a C-section, allowing you to return to normal activities sooner.
- Lower Risk of Complications in Future Pregnancies: Each C-section increases the risk in subsequent pregnancies for serious placental problems, such as placenta previa and placenta accreta. A successful VBAC avoids these future risks.
- Personal Experience: Many women desire the experience of a vaginal birth, and a successful VBAC can be an incredibly empowering and fulfilling experience.
Understanding the Primary Risk: Uterine Rupture
The main concern with a TOLAC is the risk of uterine rupture. This is a rare but very serious complication where the scar from the previous C-section tears open during labor. The risk of this happening is low, occurring in less than 1% (about 1 in 200) of women who attempt a TOLAC with the most common type of incision.
Because of this risk, a TOLAC should always take place in a hospital that is equipped to handle an emergency C-section, should the need arise.
Are You a Good Candidate for VBAC? Key Factors
The American College of Obstetricians and Gynecologists (ACOG) has identified several factors that help predict the likelihood of a successful VBAC.
Factors That Increase Your Chance of Success:
- A Previous Vaginal Delivery: If you have successfully delivered a baby vaginally, either before or after your C-section, your chance of a successful VBAC is very high (often over 90%).
- Reason for Your Prior C-Section: If your C-section was for a reason that is not likely to be present in this pregnancy (e.g., the baby was in a breech position or there was fetal distress), you are a good candidate.
- Spontaneous Labor: Your chances are highest if you go into labor on your own, without the need for induction.
Factors That May Decrease Your Chance of Success (or be Contraindications):
- Type of Uterine Incision: This is the most critical factor. A low-transverse ("bikini cut") incision, which is the most common type, has the lowest risk of rupture. If you had a high vertical ("classical") incision or a T-shaped incision, a TOLAC is generally not recommended due to a much higher risk of rupture. Your operative report from your previous C-section will have this information.
- Reason for Prior C-Section was "Failure to Progress": If your previous C-section was because your cervix did not dilate fully or the baby did not descend, there is a chance this could happen again, slightly lowering the VBAC success rate.
- Need for Induction: While induction is possible for a TOLAC, certain methods (like using prostaglandins for cervical ripening) may increase the risk of rupture and are often avoided.
- Pregnancy Factors: A suspected large baby (macrosomia), a pregnancy that goes far past the due date, or carrying multiples can lower the chances of success.
- Short Interpregnancy Interval: A shorter time (less than 18 months) between pregnancies may slightly increase the risk of rupture.
Shared Decision-Making: The Conversation With Your Provider
The decision about whether to plan for a TOLAC or a repeat C-section is a classic example of shared decision-making. There is no single right answer for everyone.
You and your healthcare provider will have a detailed discussion, weighing your personal preferences against your specific medical history and risk factors. They can use clinical prediction models (which are more complex than this guide) to give you a more personalized success score. Together, you will create a birth plan that feels right for you, prioritizing the health and safety of both you and your baby.
For many women, a TOLAC is a safe and rewarding path. Being well-informed about the factors involved is the first step toward making an empowered choice.
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For women who have previously had a Cesarean delivery (C-section), a subsequent pregnancy brings up an important question: "Can I have a vaginal birth this time?" The answer is often yes. A Vaginal Birth After Cesarean, or VBAC, is a safe and viable option for many women. The process of laboring for a VBAC is called a Trial of Labor After Cesarean (TOLAC). This guide is designed to explain the benefits, risks, and the key factors that help you and your healthcare provider decide if a TOLAC is a good choice for you.
This is an educational guide, not a predictive tool. The decision to pursue a VBAC is highly individual and must be made in close consultation with your obstetrician or midwife, who can assess your specific medical history and circumstances.
Why Consider a VBAC? The Benefits
Choosing to attempt a VBAC can have several advantages over a scheduled repeat C-section:
- Avoids Major Abdominal Surgery: A VBAC allows you to avoid the risks associated with another surgery, such as infection, blood loss, and longer recovery times.
- Shorter Recovery Period: Recovery from a vaginal birth is typically faster and less painful than recovery from a C-section, allowing you to return to normal activities sooner.
- Lower Risk of Complications in Future Pregnancies: Each C-section increases the risk in subsequent pregnancies for serious placental problems, such as placenta previa and placenta accreta. A successful VBAC avoids these future risks.
- Personal Experience: Many women desire the experience of a vaginal birth, and a successful VBAC can be an incredibly empowering and fulfilling experience.
Understanding the Primary Risk: Uterine Rupture
The main concern with a TOLAC is the risk of uterine rupture. This is a rare but very serious complication where the scar from the previous C-section tears open during labor. The risk of this happening is low, occurring in less than 1% (about 1 in 200) of women who attempt a TOLAC with the most common type of incision.
Because of this risk, a TOLAC should always take place in a hospital that is equipped to handle an emergency C-section, should the need arise.
Are You a Good Candidate for VBAC? Key Factors
The American College of Obstetricians and Gynecologists (ACOG) has identified several factors that help predict the likelihood of a successful VBAC.
Factors That Increase Your Chance of Success:
- A Previous Vaginal Delivery: If you have successfully delivered a baby vaginally, either before or after your C-section, your chance of a successful VBAC is very high (often over 90%).
- Reason for Your Prior C-Section: If your C-section was for a reason that is not likely to be present in this pregnancy (e.g., the baby was in a breech position or there was fetal distress), you are a good candidate.
- Spontaneous Labor: Your chances are highest if you go into labor on your own, without the need for induction.
Factors That May Decrease Your Chance of Success (or be Contraindications):
- Type of Uterine Incision: This is the most critical factor. A low-transverse ("bikini cut") incision, which is the most common type, has the lowest risk of rupture. If you had a high vertical ("classical") incision or a T-shaped incision, a TOLAC is generally not recommended due to a much higher risk of rupture. Your operative report from your previous C-section will have this information.
- Reason for Prior C-Section was "Failure to Progress": If your previous C-section was because your cervix did not dilate fully or the baby did not descend, there is a chance this could happen again, slightly lowering the VBAC success rate.
- Need for Induction: While induction is possible for a TOLAC, certain methods (like using prostaglandins for cervical ripening) may increase the risk of rupture and are often avoided.
- Pregnancy Factors: A suspected large baby (macrosomia), a pregnancy that goes far past the due date, or carrying multiples can lower the chances of success.
- Short Interpregnancy Interval: A shorter time (less than 18 months) between pregnancies may slightly increase the risk of rupture.
Shared Decision-Making: The Conversation With Your Provider
The decision about whether to plan for a TOLAC or a repeat C-section is a classic example of shared decision-making. There is no single right answer for everyone.
You and your healthcare provider will have a detailed discussion, weighing your personal preferences against your specific medical history and risk factors. They can use clinical prediction models (which are more complex than this guide) to give you a more personalized success score. Together, you will create a birth plan that feels right for you, prioritizing the health and safety of both you and your baby.
For many women, a TOLAC is a safe and rewarding path. Being well-informed about the factors involved is the first step toward making an empowered choice.