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Comparing Fetal Death and Injury: VBAC vs. Amniocentesis/CVS

Often the difference between marketing and reality is huge.  OBs tell you that you can have the birth you want… until you check into the hospital and learn “That’s not the way we do things.”  As you stare at a poster entitled “Birthing Positions,” your L&D nurse insists that you stay in bed… and push on your back with your knees by your face.  The marketing of invasive prenatal tests, such as amniocentesis and CVS, and VBACs is no different.  I understand that malpractice suit fears, insurance limitations, and just laziness play a huge role into the accessibility of VBAC, but the fact remains that miscarriage is more likely to happen after an amniocentesis or CVS, than fetal death or injury from a VBAC.

Frequency of Procedures

According to the CDC, in 2000 there were 96,698 amniocenteses.  The rate of amniocentesis is falling: “The overall rate for amniocentesis continued to decrease. The amniocentesis rate was 1.7 percent of all live births in 2003, down from 1.9 percent in 2002 and 3.2 percent in 1989.”  (1)

According to the CDC, in 2003 10.6% of women with a prior cesarean had a VBAC resulting in 51,602VBACs. (2)  The remaining 89.4% had repeat cesareans resulting in 434,699 surgeries.  Repeat cesareans represented 38.8% of all the cesareans (1,119,388) performed that year. (3)

What is an amniocentesis and how does it differ from a chorionic villi sampling (CVS)? 

ACOG explains:

Amniocentesis is an invasive diagnostic procedure used to detect certain birth defects and is performed early in the second trimester (16-20 weeks gestation). Amniocentesis involves inserting a needle through the abdomen into the uterus to collect a small sample of amniotic fluid for testing of chromosomal abnormalities in the fetus. CVS also is an invasive procedure used to detect certain birth defects but is done in the first trimester (10-12 weeks gestation). CVS collects a small sample of chorionic villi (tiny parts of the placenta) cells from the lining of the uterus either by inserting a slender needle through the abdomen into the placenta or by inserting a very thin plastic tube into the vagina, through the cervix and into the placenta.

For more information on these procedures, go here: CVS and amniocentesis.

What are the risks of amniocentesis versus CVS?

As you read, think about the specific language used as well as who benefits when a procedure is encouraged and discouraged.

From a March of Dimes Fact Sheet dated August 2005 (emphasis mine):

Serious complications from second-trimester amniocentesis are uncommon. However, the procedure does pose a small risk of miscarriage.  According to the Centers for Disease Control and Prevention (CDC), between one in 400 and one in 200 women have a miscarriage after amniocentesis. . . Studies suggest that the risk of miscarriage after first-trimester amniocentesis may be 3 times higher than the risk after second-trimester amniocentesis.

From this statement, we can extrapolate that the risk of miscarriage in a first-trimester amniocentesis is between one in 66 (1.5%) and one in 133 (0.75%).

From an ACOG press release dated August 31, 2006 (emphasis mine):

The risk of pregnancy loss (miscarriage) after undergoing chorionic villus sampling (CVS) to detect birth defects is lower than previously thought and essentially carries no higher a risk than the more commonly used amniocentesis procedure, according to new research published in the September [2006] issue of Obstetrics & Gynecology. While both procedures carry a small risk of causing miscarriage, this study found that the miscarriage risk attributable to CVS is the same as the risk of 1 in 370 seen with amniocentesis when adjusting for the earlier gestational age of the CVS procedure.

Caughey 2006 is the study ACOG references above.  Including almost 31,000 women, it found that the rate of postprocedure amniocentesis and CVS miscarriage fell from 1983 to 2003.  The amniocentesis “postprocedure loss” decreased from 0.54% to 0.27% with an average loss of 0.46%.  They also found the CVS postprocedure loss over the same period of time to drop from 3.59% to 1.16% with an average loss of 2.35%.  (View the chart.)

There is another chartshowing the risk of loss based on gestational age.  Miscarriage rates ranged from approximately 3.75% for a CVS at 9 weeks down to 2% for a CVS at 13 weeks to just over 1.5% for an amniocentesis at 14 weeks to the lowest point of just below 0.5% at 18 weeks and then it increases to just over 1% at 20 plus weeks.

The study concludes, “The loss rates for both amniocentesis and CVS at our institution have decreased over time. Because the decrease in loss rate for CVS has been greater, there is no longer a statistically significant difference between the two.” How is it that 1.16% is statistically the same as 0.27%?  Seems to me, that it’s quadruple the risk.

ACOG then uses this information to mislead the public when they state the the miscarriage rate from CVS is 0.27%.  The Caughey 2006 study clearly states that the rate of loss from CVS is 1.16%.  Yet since the study claims 1.16% and 0.27% are “statistically insignificant,” ACOG uses this opportunity to pick the smaller number and report the rate of loss for CVS as 0.27%.  ACOG uses this study to boast how safe CVS and amniocentesis are when the risk is greater than the risk of fetal death or injury as a result of VBAC.  The question is, why?

How does the risk of amniocenteses and CVS induced miscarriages compare to the risk of uterine rupture and fetal injury or death in VBAC labors?

The risk of uterine rupture is 1 in 250 (0.4%) (one prior cesarean, horizontal incision, spontaneous labor), the risk of adverse fetal outcome in a VBAC labor is 1 in 2000 (.05%) (Landon 2004.)

Miscarriage is death of a baby.

Uterine rupture does not equal death (mortality) or injury (morbidity) for mom or baby.

The March of Dimes, which quotes rates of miscarriage comparable with rates of uterine rupture in a VBAC, describes the risk of miscarriage vis-à-vis amniocentesis as “small” and “uncommon.”  And these numbers are 5 – 20 times higher than the risk of fetal death or injury from a VBAC.

ACOG themselves, describes the risk of 1 in 370, as “small” as does the American Academy of Family Physicians.  This is 5.4 times greater than the risk of fetal death or injury a VBAC.

Source Complication
1st Trimester Amniocentesis March of Dimes 0.75% – 1.5% risk of miscarriage (1 in 66 – 133)
2nd Trimester Amniocentesis March of Dimes 0.25% – 0.5% risk of miscarriage (1 in 200 – 400)
2nd Trimester Amniocentesis Caughey 2006 0.27% risk of miscarriage (1 in 370)
CVS ACOG Statement 8/31/2006 0.27% risk of miscarriage (1 in 370)
CVS Caughey 2006 1.16% risk of miscarriage (1 in 86)
VBAC Landon 2004 0.4% risk of uterine rupture (1 in 250)
VBAC Landon 2004 0.05% risk of fetal death or injury (1 in 2000)

Why is it, when a woman wants a diagnostic test, this risk is “acceptable,” yet when a woman with a prior cesarean wants a vaginal birth, the normal biological consequence of pregnancy, the smaller risk is unacceptable?

Help me understand how a woman seeking VBA2C (vaginal birth after 2 cesareans), that has an uterine rupture risk of approximately 0.9% (Landon 2006), is hard pressed to find any care provider willing to attend her birth, let alone a VBA1C women facing a 0.4% risk, yet doctors willingly perform a procedure that has a 1.16% miscarriage rate?

If it’s about preserving the lives of babies, whether 20 weeks or 40 weeks gestation, why even offer an optional test?  Because it’s the “choice” of the patient?  So, why can’t women “chose” VBAC?  Because malpractice insurance companies deem it to risky?  Yet, those same insurance companies cover amnios and CVSs?  Is it because women don’t sue when they miscarry at 20 weeks?  Because the life of a otherwise healthy first or second trimester baby has less value than a full-term baby?  Maybe because miscarriage is so common, or seen as a “lesser” event, that the risks of amnios are described as small and uncommon?

OBs argue that women with prior cesareans should have repeat cesareans because there is no way of knowing what woman will rupture and ruptures can have dire consequences – babies dying, and, more rarely, moms dying.  But one can argue the same thing with amniocentesis and CVS.  We have no way of knowing what otherwise healthy, normal baby will die as a result of this optional testing.  Yet, OBs opt not to attend VBACs and still offer amniocentesis.

I have yet to hear of one person, at the park by a fellow mom or on the exam table by an OB, make a woman feel guilty about having an amniocentesis because she might kill her baby, yet that is the exact language OBs use when they “counsel” VBAC seeking women.  Women are treated as if they are willing to kill their baby for an “experience.”  And that’s exactly what some OBs think vaginal birth is: an experience.  And since it’s just an “experience,” we can easily minimize its importance, marginalizes its benefits, and pretend it really doesn’t matter how babies are born.

Women seeking VBAC are treated as if they are accepting an excessive amount of risk.  Yet, I have met women who would not VBAC because the perceived risk is to great, yet, when their OB suggested an amniocentesis, they consented.  When I was pregnant with my son, and planning a home VBAC, I knew a woman who had an amniocentesis for “advanced maternal age.”  She couldn’t believe that I was planning a VBAC.  She thought the risk was to high, yet, she clearly didn’t understand that her amnio was more likely to result in the death of her baby.  Do you think her OB was upfront with her about the risks of amnios? How do you think that same OB counsels women about VBAC?  Does s/he put the risk into perspective saying, “Amnios are riskier than VBACs” or does s/he say, “Why risk uterine rupture when we can just schedule a cesarean?”  This illustrates the difference between what is true and what we are told.

I have yet to hear of hospitals banning amniocenteses, doctors refusing to perform them, or malpractice insurance dropping OBs if they do.  And it sounds absurd for any of these things to happen.  Yet, this is exactly what has happened in terms of VBAC and the number of VBAC-friendly hospitals and care providers continues to decrease.

Many people assume that VBAC is risky simply based on the fact that hospitals have banned them and some OBs refuse to attend them.  Once most women hear “VBAC ban” or learn that their gynecologist of 10 years “doesn’t do them,” their quest for information stops.  They don’t go the extra step and actually question why or do the research themselves.  And why should they?  We hire OBs for the same reason we hire car mechanics – for their knowledge and expertise.  We assume that they will make a diagnosis, guide us through our options, weight the pros and cons, leaving us with all the information we need to make an informed decision.

Instead, OBs tell us what they are willing to do and we accept their word without question.  So we assume that amnios are “safe” simply because OBs perform them and VBACs aren’t because they don’t.  Unfortunately, we can’t blindly trust OBs:

As long as you are of legal age and able to think clearly, logically, and coherently for yourself, you should never cede that responsibility [to make your own health decisions] to anyone else – not your doctor, not your friends, not to your family, not to the heath gurus, and especially not the media.  Unlike many among the health police force, I believe that you are easily smart enough to evaluate the news.  You really have no choice.  People are finally realizing that they cannot trust the health industry machine anymore.  That means you must come to rational, intelligent decision based on the best that science has to offer.  (Eat, Drink, & Be Merry by Dean Edell, MD)

I could have hired any OB within a 50 mile radius and requested an amniocentesis and/or repeat cesarean.  Yet, how many of those OBs would have attended my VBAC?  A fraction.  And how many do I believe were truly supportive of VBAC?  One.

A Less Evasive Alternative & Following the Money

In my research, I came across a presentation created by Xenomics, a “developer of next-generation molecular diagnostics products that address important health problems worldwide.”  Xenomics proposes a fascinating new technology where they are able to utilize the fetal cells found in the mother’s urine for prenatal testing.  (You can read more about this technology here.)  Of course, like any new product, the market needs to be defined to determine the financial potential of that product.

A slide in their presentation describes the prenatal testing market:

1.6 million recommended amniocentesis
• At $400 = $650 million
0.2 million amniocentesis performed annually
• At $400 = $80 million
Created Market $500 m – $1.0 b
U.S. Market Only – Worldwide approx. 2X

They quote the cost of amnios as $400 which seems to be on the low-end of the scale.  One source stated that the average cost of amniocentesis to be $1500 however, I think the real number is higher because it’s not just the test you are paying for – it’s all the analysis and counseling as well.  One group charges $4225 which covers the amnio, ultrasound, chromosomal analysis of the amnio specimen, and genetic counseling.  The procedure itself only takes 10 minutesto perform.

How does this compare with the cost of vaginal birth and cesarean section?  Three different sources show how the costs of each event increased over the span of 13 years:

According to figures from the American College of Obstetricians and Gynecologists, the cost of these 982,000 Caesarean births at an average cost of $7,826 was $7.7 billion. Comparatively, there were 3.1 million babies born in the U.S. in 1990 in regular vaginal deliveries that averaged $4,720 apiece, costing Americans more than $15 billion.

In 1996, cesarean delivery costs average $11,450 compared to $7,090 for uncomplicated vaginal birth. (Source: Mushiniski M. Average Charges for uncomplicated vaginal, cesarean, and VBAC deliveries: Regional variations, United States, 1996. Statistical Bulletin, Met Life July-September 1998.)

The average charge for childbirths was $8,300. The aggregate charges (i.e., national bill) for these hospital stays totaled over $33 billion. The average charges associated with uncomplicated C-sections were $11,500, which is more than $5,000 greater than the mean charge for all routine vaginal deliveries.  (Statistical Brief #11: Hospitalizations Related to Childbirth, 2003)

While it may sound crass, to reduce medicine down to money, the fact is, amnios are an optional test.  An optional test that costs a lot of money.  Until we are able to “beam the baby out” Star Trek style, babies need to be born one way or another and we have two choices: vaginal or cesarean.  It seems to me that prenatal testing like amnios and CVS, as well as surgical births, are more efficient money makers than vaginal birth.  They take less time in the hospital, less time waiting around for a baby to be born, and can be scheduled, unlike a spontaneous vaginal birth.  It’s simply another revenue stream, another product to offer women.  Note that from 1990 – 2003, cesareans cost 139% – 165% more than vaginal births.  Seems that more money is to be made, in less time and during normal working hours, if a woman has her amnio and then schedules her cesarean than if she declines prenatal testing and has an unmedicated, intervention-free vaginal birth.

Marketing – Reality = Who Benefits?

When making any medical decision, it’s important to understand the risks, benefits, and options.  I’m not saying amniocenteses and CVSs shouldn’t be performed or that the women who have them are reckless.  I think the decision should be in the hands of each woman.  Since the primary place that most people get their medical advice is from their doctor, risks need to be put into perspective.  Unfortunately as we have seen here, how a procedure and its risks are portrayed can vary greatly based on the objective of the person or organization giving you the information.  This is why it is vitally important for you to do just a touch of research and ask your doctor questions.  There is nothing wrong with getting a second opinion either.

When doctors and ACOG want to encourage a procedure, or “honorably” leave it up to the patient under the guise of “choice,” like amnios, CVSs, and repeat cesareans, they minimize the risks, yet, when they want to discourage a procedure, like VBAC, they pull out the dead baby card.  How many women were talked out of an amino by their OB via the dead baby card?  Or, was this decision respectfully left in the hands of the patient?  Was she given the choice?  Ironic how most women can chose to have an amnio, chose to have a CVS, chose to have a repeat, or even primary cesarean, but when it comes time to chose a VBAC, our options are increasingly limited.  We are lead to believe that it’s a “choice” to have invasive prenatal testing, or surgery without medical indication, but it’s selfish and dangerous to seek a VBAC.

It’s fascinating how procedures have been marketed leaving American society with the notion that VBAC risks are unreasonable and amnio/CVS risks are acceptable, when the reality is, you are more likely to end up with a dead baby with your amnio or CVS than you are with VBAC.  As Dr. Edell says, “People are finally realizing that they cannot trust the health industry machine anymore.  That means you must come to rational, intelligent decision based on the best that science has to offer.”  Exactly.

If you are considering an amniocentesis, I highly recommend you go here for a complete analysis.


(1) This is the latest, most recent data I could find.  In the more recent Births:Final Data Reports, hard numbers for amniocentesis are not mentioned.

(2) The National Vital Statistics Report Birth:The Final Data for 2005, does contain VBAC information for that year, but the data is not as complete as the 2003 figures.  Per Birth:The Final Data for 2005:

Information on Method of Delivery is reported on both the 2003 Standard Certificate of Live Birth (revised) and 1989 Standard Certificate of Live Birth (unrevised). However, the format and wording of the Method of Delivery item on the revised standard certificate differs from that of the unrevised standard certificate (see ‘‘Technical Notes’’). The unrevised Method of Delivery item asks a direct question on
whether the birth was vaginal, VBAC, or a primary or repeat cesarean delivery. In contrast, the revised Method of Delivery item asks if the final route of delivery was vaginal (with or without forceps or vacuum assistance) or a cesarean delivery. Information on type of vaginal (vaginal or VBAC) and type of cesarean delivery (primary or repeat) is calculated from the response to a question under a different item, Risk Factors in this Pregnancy, which asks if the mother had a previous cesarean delivery. As a result, although data on total cesarean delivery appear very comparable, data on VBAC, primary, and repeat cesarean deliveries are not directly comparable between revisions, and are presented separately for revised and unrevised reporting areas.

(3) Trends in Cesarean Rates for First Births and Repeat Cesarean Rates for Low-Risk Women: United States, 1990–2003 is a great piece on how the rates of VBAC and repeat cesarean have changed from 1990 – 2003 and here is a great chart showing vaginal birth, VBAC, primary cesarean, and repeat cesarean rates by age.

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