VBACs or vaginal birth after a cesarean is when a woman gives birth vaginally after having a C-section delivery of her previous pregnancy.
In the past, women who delivered via cesarean section would always continue with this method in subsequent pregnancies, but this started to change in the 1970s. This is partly because "trials of labor after cesarian delivery" or TOLAC became more common as C-sections were more common, and they have increased slightly in recent years.
Every woman should talk to her doctor about delivery options, but there are several reasons to consider a vaginal birth after a past C-section. Vaginal births have a shorter recovery time, and they have less impact on future pregnancies — multiple C-sections increase the risk of complications like placenta previa or placenta accreta.
C-sections come with some surgical risks, as well, like bleeding, infection, and blood clots.
One factor determining whether a woman should consider VBAC is the type of uterine incision the doctor used for their previous delivery. After a C-section, scar tissue forms on the uterus at the incision site, and some locations are more likely to rupture than others.
A low transverse cut is the most common. It goes horizontally across the lower part of the uterus and is least likely to rupture. A low vertical incision is also in the lower part of the uterus, but it goes up-and-down and has a higher risk of rupture. A classical or high vertical incision goes up-and-down on the upper part of the uterus and is most at-risk for rupture in the next birth.
Some women are better candidates for VBACs than others. Women pregnant with one baby are good candidates if they have a history of one or two low transverse C-sections or one C-section with an unknown incision type, unless the doctor suspects a high vertical incision.
For twin pregnancies, a woman with a history of one low transverse C-section could be considered a good candidate for future vaginal births.
Not all pregnancies are candidates for VBAC. In addition to a high vertical or classic incision, other factors that decrease the likelihood of a successful vaginal birth after a C-section are a prior uterine rupture, prior uterine surgery, history of multiple C-sections, a body mass index or BMI higher than 40, or pregnancy with triplets or higher-order multiples.
Other factors can also indicate that VBAC will be unsuccessful, including induction of labor, stalled labor, advanced maternal age, excessive pregnancy weight gain, and preeclampsia.
Labor during routine vaginal birth and VBAC are similar. When a woman attempting VBAC goes into labor, the doctor will likely monitor the baby's heart rate closely and be prepared to do an emergency C-section if needed.
VBACs should always happen in medical facilities equipped to handle an emergency C-section, and the mother should be aware of the possibility that a C-section may end up being the best and safest option.
The success rate for VBAC is between 60 and 80 percent. Women who had a previous C-section due to a non-recurring issue — such as a breech delivery — are more likely to have a successful VBAC as opposed to those with recurring issues like high blood pressure, diabetes, and infections like HIV or herpes.
Other indicators that a VBAC will be successful are spontaneous labor and a history of a prior vaginal delivery.
There are risks and benefits to both repeated C-sections and VBACs, and the decision of which to pursue depends on many factors. The biggest risk with VBAC is uterine rupture.
Repeated C-sections may result in both short and long-term issues, too, though. Each C-section carries the same risks as abdominal surgery — such as infections and bleeding — and the more C-sections a woman has, the more risks there are for future pregnancies. The placenta may attach to the scar, which can cause severe bleeding and, in severe cases, require early delivery and a possible hysterectomy.
Uterine rupture is uncommon, affecting less than one percent of VBACs with one previous low-transverse incision and between one and two percent of VBACs with two previous low-transverse incisions.
It occurs when the uterus separates at the site of the previous C-section incision. This medical emergency prompts the doctors to take the mother for abdominal surgery to deliver the baby and address any additional complications. The mother may experience significant bleeding and require a hysterectomy. A uterine rupture can cause many serious problems for the baby, primarily because it interrupts the transfer of oxygen and blood between the mother and the baby.
The most common sign of uterine rupture is an abnormal fetal heart rate, which is present in 70 percent of rupture cases. Doctors carefully watch the fetus during labor using continuous heart rate monitoring. If any concerns arise, the doctor will perform a cesarian delivery immediately.
Other signs of a uterine rupture include a change in uterine contractions, severe abdominal pain, blood in the urine, or sudden loss of fetal activity. The event is a medical emergency.
After a successful VBAC, the mother delivers the placenta, and postpartum care proceeds similarly to routine vaginal delivery. If the doctor suspects any issues with the C-section scar, they may perform a manual examination. These defects do not require repair unless the mother is actively bleeding.
If the mother does show signs of an active bleed after delivery, like low blood pressure, uterine rupture is possible and immediate intervention may be necessary.
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