Monday, May 19, 2014

What a VBAC Calculator Shows

This morning I noticed this intriguing post in our local ICAN group's Facebook page:

I know this isn't an active group, but this is the only one of my groups where it seems appropriate to post this. Does anyone know where I can find info about the VBAC rates for home births and hospital births? I found this cool VBAC calculator, but it doesn't account for birth setting.

A Vaginal Birth After Cesarean calculator? Really? So I decided to try it.

It is always important to know who you are playing with so I investigated who created this calculator. OK it says it is based on data collected from an article "Development of a nomogram for prediction of vaginal birth after cesarean". A nomogram? Huh? That is just a geometric way of looking at multiple variables. The data set came from the Maternal-Fetal Medicine Unit Network. Here is their mission statement: "The MFMU Network conducts clinical studies to improve maternal, fetal and neonatal health emphasizing randomized-controlled trials. The aims of the Network are to reduce maternal, fetal and infant morbidity related to preterm birth, fetal growth abnormalities and maternal complications and to provide the rationale for evidence-based, cost-effective, obstetric practice." They are a network of university based hospitals. These teaching hospitals are where the births happened that form the statistics to base this calculator upon.

First the questions they ask to help them calculate are telling. They want your age and body mass index. Don't know your BMI? Don't worry they'll calculate it for you. They want to know if you have a "proven pelvis". What's that? It is a woman who has either had a vaginal birth before or after a cesarean. In other words at some point a baby "fit" through. They want to know if your cesarean was for lack of progress dilating, lack of progress moving the baby through your pelvis or some other reason. Other reasons could be twins, breech, high blood pressure, fetal distress, maternal fever, etc. They just lump all the other reasons into one category. Most distressing to me are their questions about race. They break it down by African-American, Hispanic and all others lumped together. What the hell? What on earth should race have to do with it?

So here is what I found when I did some calculations.  I kept all other factors the same except the one I was looking at. Trying to compare apples to apples. Let's look at age first.

They obviously feel age matters. I changed the age from 18 to 30 to 35. 
I had between 7% to 10% less chance of successfully VBACing at 30 than at 18 years old. The low end reflects women who progressed on their predetermined schedule. The top end reflects women who fell off the time chart plus were heavier. At 35 it drops again. Now I have 10% to 15% less chance depending on the other factors. Ugh! Obviously age is NOT something you can do something about or can you? How many 35 year-olds do you know? I have worked with many and some have the physical health of a 40 year old while others could pass for being in their twenties.

By adding 70 pounds to a white woman with no previous vaginal births and allowable progress during labor/pushing she has lowered her chances of VBAC success by 12%. If she had a "failed" labor the numbers move down to 16% because of the additional pounds alone. This may make some sense because weight can cause confounding health issues, such as high blood pressure.So if you want to VBAC stack the decks in your favor by starting at a healthy weight. Oh wait! If you want to avoid that first section be a healthy weight before you get pregnant and then work with someone who knows about pregnancy nutrition to stay on track.

Arrest of Labor
This is defined as absence of progress. So of course one must FIRST note that progress is a very subjective animal. The good news is this calculator says if you had a surgical birth for arrest or "failure" either during dilation or pushing your chances are only 9% to 12% less than the woman who didn't. As a doula I know it is critically important to look at WHY you stopped progressing or weren't progressing fast enough. Was the baby in a poor position? Was this a failed induction? Why were you induced? Too long past due date? How far was too long? Baby "suspected" of being too large? How large was he or she really? Induced for other health concerns, blood pressure, diabetes, etc.? Perhaps your water broke and labor didn't start quickly enough so you were given labor initiating drugs. Did you have an epidural? At what point in the labor? I can't stress how important it is to obtain ALL your records and to go over them with an experienced doula or midwife. Perhaps your "failure" to progress was actually THEIR failure. 

Here is where they doubly fail women. Be prepared to get angry.
I went back and changed only race as a factor. So let's look back at the age issue WITH race added in. If I am a 30 year old woman of color I had a 10 to 16% less chance than an 18 year old. While a white 30 year old has a 7% to10% less chance.  And at 35 I as a white woman would have 10% to 15% worse odds but as a woman of color it plummets to a 21% less chance of success. Excuse me? What about race with weight? If I am a 30 year old white woman with healthy weight, no vaginal births and no "failure" the calculator predicts I have a 80% success rate in their hospitals. That same woman of color? 67.2%! That is a difference of about 13%. If  I am 70 pounds heavier I have a 16% worse chance of success than my white sister. 

So now I compared the best case scenario; 18 years old, healthy weight, no arrested labor c-section, vaginal birth before and after surgical birth, White to Black or Hispanic. Shockingly the numbers say a woman of color automatically gets 4% worse chance of birthing vaginally. That my friends is systemic racism in its most insidious form. It is in how they are treated from the moment they are in their doctor's offices until the moment they are discharged from the hospital. I have witnessed this unequal treatment. Every time it has angered me. Usually it appears to anger me more than the woman trapped in it. Perhaps because she has only her own experience to compare, whereas I can compare her to the white women I have supported. But here the numbers are; in black and white for all to see. A disgrace.

I did not intend for this to be a post about race. I started in thinking I was going to check out this calculator and compare hospital stats with homebirth stats. But the numbers took me a different direction. Here are two links for those of you who wish to compare homebirth and hospital birth numbers. They were posted by Terri Woods of SLO Doula Connection  in response to the ICAN query. She rightly warns that homebirth midwives automatically risk out a variety of complications and so it isn't exactly apples to apples. Still it is worth noting that out of 1,354 VBAC women 87% were successful. There is no way for me to do a straight comparison because I don't know anything about age, weight, reasons for prior sections or if they have had a vaginal birth either before or after their surgical birth. 

Science and Sensibility looks at the MANA homebirth study 

Outcomes of Care for 16,924 Planned Home Births in the United States: The Midwives Alliance of North America Statistics Project, 2004 to 2009

Planning to VBAC? Hire a doula. Plan a home birth. Hire a midwife. Get healthy and stay healthy. Finally question, question, question; especially if you are a Black or Hispanic woman. 

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