ICAN of Atlanta

Statistics taken from http://consensus.nih.gov/2010/vbacstatement.htm

PDF version can be found here.

As a reference, these numbers are all in comparison to 100,000 women – so “2” would be 2/100,000 or 0.002%. VBAC *attempts* (includes those with uterine ruptures and those that end up with a C-section anyway) are listed as TOL, Elective C-sections are ERCS:

–Immediate risks–

Maternal mortality (death of mother): 3.8 TOL vs 13.4 ERCS overall (For perspective – the rate of motor vehicle-related mortality for men and women aged 25-44 is about 16)

Hysterectomy: 157 TOL vs 280 ERCS. Risks increase with each C-section (about 420 total with one prior C-section, 900 with two, 2410 with three, 3490 with four, and 8990 with five or more)

Need for blood transfusion: 900 TOL vs 1200 ERCS. This also increases with each prior C-section

Deep venous thrombosis (DVT – blood clot, which can lead to stroke): 40 TOL vs 100 ERCS

Uterine rupture (UR) : 325 TOL vs 26 ERCS overall. Keep in mind that the rate of UR in women with no previous uterine surgery is about 6 (in 100,000 of course)

The ERCS UR rate is significant because it reminds us that choosing one doesn’t erase the possibility of UR. It is also important to note that most URs don’t lead to fetal death because of the ability to do an emergency C-section. Some may argue that this is taking advantage of the hospital system to make it less dangerous, but that safety net is the whole point of using a hospital in the first place. That is the same safety net that would be needed in case of a placental abruption or prolapsed cord – both of which can occur during any labor.

Birth trauma to baby (specifically brachial plexus injury): 180 TOL vs 30 ERCS. (Again, please note that choosing an ERCS doesn’t completely take away this risk and that the TOL rate is likely the same as the non-VBAC vaginal birth rate.)

Perinatal mortality (20 weeks to 28 days of life): 130 TOL vs 50 ERCS. I’m am not yet sure how these numbers were reached specifically since it seems a lot can happen between 20 weeks gestation and 4 weeks old that had nothing to do with delivery method, but the report did mention that the TOL rate is comparable to the perinatal mortality rate in first time moms and that overall mortality (irrespective of delivery method) is 1073.

Also, it appears that ERCS may lead to increased rates of respiratory problems and possibly asthma, but this comes from studies comparing general C-sections to general vaginal births so the numbers aren’t included in this VBAC statement.

A note on perinatal mortality and URs – According to the NIH numbers, babies die in about 6% of the URs, with those at term (not preemies) tending to be less than 3%. Extrapolating that, using the overall numbers of 325 TOL ruptures and 26 ERCS ruptures and the overall fetal mortality rate of 6%, that would indicate a mortality rate of about 19.5 TOL vs 1.5 ERCS due to UR.

What is significant about this is that while women are often told that attempting a VBAC will put their baby’s life in jeopardy because of the risk of UR, the risk of a baby dying because of a TOL UR is actually fairly comparable to the risk of a mother dying as a result of an ERCS – and both are quite rare.

I know that many doctors/nurses who practiced in the 90s (when UR became a bigger concern) seem to remember more URs than these statistics would indicate. Please remember that at that time less was known about what causes ruptures and many things that are now known to be very dangerous were used at that time without knowing the possible harm. For instance, induction using prostaglandins has now been found to increase the UR rate by up to 15 times the baseline rate. Among these is cytotec, which currently has a warning label that says it should NOT be used in pregnant women because of the risk for rupture, even in those with no prior c-section.

–Additional long-term risks—

C-section delivery is associated with higher rates of placental abnormalities in future pregnancies, and the rates increase with each progressive C-section.

Placenta previa (where the placenta covers the cervix), for instance, has a rate of 900 after one C-section, 1700 after two, and 3000 after three or more. This may not seem like a big concern if you were planning a C-section anyway, but previas increase the risk of hemorrhaging, hysterectomy, and accreta (placenta growing into/through the uterus) – even when a C-section is done before any labor starts.

And looking at the chance of the placenta growing into/through/past the uterus (placenta accreta, increta, and percreta) alone there is a risk of 319 after one C-section, 570 after two, and 2400 after three or more. These are pretty scary risks that would occur in pregnancy (so it wouldn’t matter if the mother wanted a TOL or ERCS for that pregnancy) and most of those rates are more than the risk of UR in a TOL.

Also, a prior C-section is associated with increased risk of abruption (placenta detaching from the uterus), chronic pain, ectopic pregnancy, stillbirth, and infertility, though it is not clear if these risks increase with additional C-sections.

Other problems that do increase with each C-section include clinically significant adhesions, complications during a future repeat C-section, and bowel and ureteral (like bladder) injuries. And, ironically enough, some women also experience pelvic floor disorders even if they have had only C-sections.

The bottom line here is that these future risks should also be taken into consideration if a mother would like children after the current pregnancy. According to ACOG’s 2004 VBAC guidelines this should be considered if the mother is even 10-20% certain that she would like another child after this one – so basically if she is even considering the idea.