/ Maggie Koerth-Baker / 8 am Mon, Jun 2 2014
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  • How to have an evidence-based pregnancy

    How to have an evidence-based pregnancy

    There's more than one right way to have a baby. What Maggie Koerth-Baker learned about evidence-based pregnancy, risk, and the choices we make about healthcare.

    Can you have a beer while you’re pregnant?

    Is it safe to give birth at home, instead of in a hospital or birth center?

    Other than the fact that they both concern pregnant women, these two questions don’t seem to have a lot in common. Truth is, though, they’re closely intertwined. Both are implicitly expect a solid “yes” or “no” response. And, in both cases, solid “yes” or “no” answers are sorely lacking. Instead, what you get, when you look at the evidence, is a collection of data that tells you something about risk … but not really enough to tell you exactly what decision you ought to make about that risk.

    These two questions are representative of many preggo-centric healthcare decisions. They also serve as brilliant examples of why “evidence-based medicine” might not mean what you think it means.

    Several months ago, I set out to read a bunch of pregnancy books and report back to you on some of my favorites. I wanted to put together a list that would appeal to pregnant science dorks — those of us who enter the world of reproduction thinking about it less as a sacred, spiritual journey and more as a chance to participate in a really awesome DIY experiment. (I am my own 3D printer! Jealous, gentlemen?) I found eight books that filled different niches in my library. All of them put a heavy emphasis on scientific research and on not just telling me what we know, but explaining why we think we know it. All of them taught me stuff that was cool and useful and helped me think about my own pregnancy and upcoming parenthood in a different way.

    But I noticed there was something else they all had in common, as well. None of them were big on flat-out telling pregnant women what was right and what was wrong. If you set out to read these books hoping for a set of tidy rules that would make you the best pregnant lady ever, you were going to be disappointed. Ditto if you were looking for a guide to the ideal birth experience. Mega ditto if you were hoping for tricks that would ensure your baby turns out to be smarter, less weepy, and a better eater and sleeper than all the other babies in your neighborhood.

    And that seems surprising. After all, the whole reason we look to evidence is because it’s supposed to produce better outcomes than relying on anecdotes, tradition, trendiness, and/or Dr. Oz. Evidence is supposed to be the cooly rational thing that separates us from the unwashed, emotional masses. Shouldn’t the evidence-based books be more confident in telling you exactly what to do to produce the best possible outcome, rather than less?

    “People have misunderstood evidence-based medicine as cookbook medicine,” Jeremy Howick told me. He’s a research fellow at Oxford University’s Centre for Evidence-Based Medicine. “But David Hume says you can’t derive an ‘ought’ from an ‘is’.”

    What he means by that is that simply having evidence is not the same thing as knowing the “right” way to do something. At least, not most of the time. Not when it comes to healthcare. And those two key questions about pregnancy — Can pregnant women drink? Is homebirth safe? — are brilliant examples of why this is true.

    There have been studies done looking at the outcomes of both questions. But, in both cases, none of those studies are ideal. In fact, ideal studies probably aren’t possible here, because they would require you to randomly assign pregnant women to make decisions they don’t necessarily want to make. (I’m sorry ma’am, but we’re going to have to ask you to take this tequila shot every Thursday for the next 9 months.) Instead, you’re left with a lot of observational data — some stronger, some weaker. None of it telling you exactly what you want to know.

    In the case of drinking during pregnancy, the data gets messy because a lot of it is based on women remembering their own habits (sometimes years later). Other studies lump women who have one alcoholic drink a week in with women who have as many as eight — and those studies may or may not separate the women who had one single drink, every night of the week, from the women who have five drinks one night and three the next. (Differences that seem to matter a lot when it comes to how the alcohol affects a fetus.)

    For home births, a lot of the problems stem from record-keeping — if someone starts out giving birth at home and then gets rushed to the hospital with complications, some places will count that as safety demerit for home birth, other places for hospitals. There are also some big issues with the fact that the women who choose home birth are generally in demographic groups that are less likely to have pregnancy complications, to begin with.

    With both questions, the evidence gives you an opportunity to make a decision. From reading the books I read, I learned that home birth is probably safe, provided you don’t have any complications and you’re able to get to quickly get to a hospital should any arise. That’s a choice, not a prescription. Two women can look at that sentence and come to very different, evidence-based conclusions about what’s right for them.

    Same thing for drinking during pregnancy. It’s a fact that binge drinking and/or excessive drinking will cause problems for your child later in life. Sometimes, those problems are severe. Nobody knows exactly what “excessive” means, though, and there’s good reason to think that a drink a month or a drink a week aren’t going to hurt anything. Again, you’re left with a choice.

    What amount of risk are you comfortable with?

    And that’s not a question the evidence can answer for you.

    “Everybody is different. Every situation is different,” says Kay Dickersin, who directs the center for clinical trials at the Johns Hopkins School of Public Health. She gave me an example from a different side of women’s health — the options available to women who are older, done having children, and tired of suffering from abnormally long, painful, bloody periods that they can’t seem to get under control. For them, there’s two choices: A fully hysterectomy or an endometrial ablation (essentially, doctors destroy your uterine lining, but leave the uterus, itself, in place). The hysterectomy comes with a hospital stay, a higher risk of infection, and at least six weeks of post-surgical recovery time. But you know for certain you won’t be bleeding again. The ablation, on the other hand, trades a risk of not totally fixing the problem for the convenience of a faster recovery and less risk of infection.

    Which you choose isn’t really about the medical evidence — they’re both safe, they have roughly equal levels of patient satisfaction, they’re both effective. Instead, it’s about your life, your work schedule, your values and your personal preferences. What risks are you comfortable with?

    The truth about evidence-based medicine is that it actually means you have more decisions to make, not fewer. The hard facts only take you so far. To know what to do, you have to layer them up with the soft, squishy bits that make up your life — and that includes emotions, personal beliefs, and even what choices your mother and best friend made. Doing that isn’t ignoring evidence and snubbing science, Dickersin and Howlick say. It’s using the science in the way it’s supposed to be used … the only way we can use it.

    So, here’s what I learned reading evidence-based pregnancy books. I learned that I’m most comfortable having my baby in a hospital, under the care of a doctor I trust. I learned that, while I’m not willing to take the risk of home birth, I am willing to take the risk of having a beer a couple times a month in the third trimester. And I learned that, even though somebody else might make exactly the opposite decisions, we’re both still making evidence-based decisions. The best pregnancy books are the ones that acknowledge that reality and don’t try to convince you that the decisions of the author are the only right answer.

    Illo: Rob Beschizza/Shutterstock




    Notable Replies

    1. I had my daughter at a birthing center, home birthing at that time not really an option in MD (no nurse midwives had attending doctors to support a home practice). I had read and was presented by the midwifery group a lot of information about how cascading interventions starting with Pitossin and going on to epidurals lead to medically unnecessary c-sections.

      Later, when I was teaching prenatal yoga I researched this area more deeply on my own, and what I found was that the statistics were really hard to understand and presented very differently by midwives and doctors. There was no real hard and fast information about epidurals leading to c-sections. I would say that the evidence did seem to lean more toward it being better for people to have some drugs available and mostly toward the one thing that is not widely available, a doula to support the mother's emotional needs while the hospital staff cares for her medical needs.

      In the end I decided that I had no business giving medical advice and that I could only teach techniques that a mother could use during labor if she chose not to have an epidural. I think the doctors do have first hand information that the books and articles do not provide, but this difference between how midwives were interpreting data differently from doctors I found quite offensive; it seemed that people were more interested in promoting their agendas than finding out what really made for a safe delivery.

    2. c9r says:

      My wife and my first baby was delivered at home just last week. We had an exceptionally experienced and well regarded Midwife who had delivered more than 1,500 babies at home. We met several dozen people who had their babies with our Midwife, including many repeat clients. For us, the direct evidence available to us about our specific Midwife, and from people in situations similar to ours, weighed much more heavily than arguments about national averages.

      I couldn't say definitively going into the birth whether homebirth was safer or less safe. But the statistics I saw were close enough, and the risks low enough, that safety wasn't our primary decision factor. We made our choice based on quality of care. The depth of the preparation, the quality of the attention, the feeling of teamwork and shared responsibility, the respect, endemic to the midwifery model of care–in our situation–made it a clear winner.

      I get your point about demographic self-selection skewing statistics. But to be honest, this statement reads to me like: "there are some big issues with the fact that people who choose to use Ibuprofen are generally in demographic groups that are less likely to have brain tumors to begin with". Why is it a "big issue" that people make choices appropriate to their circumstances? Or do you mean that it's merely an issue for the data?

      I generally agree with this sentiment. Though I would like to comment that well-trained Midwifes are quite capable of handling emergencies. Our daughter was born with an extremely short cord. The delivery went smoothly without any intervention. But about a minute after our Baby was born, the cord detached from the placenta–a very serious emergency. The placenta needed to come out immediately. The Baby had already latched on–which wouldn't have been the case in a Hospital–and the Oxytocin helps the Uterus contract to deliver the placenta. Within 30 seconds of the cord breaking, the Midwife gave my wife a shot of Pitocin, and was ready to "go in and get it" (the placenta), if needed. Thankfully, the placenta shot out about 10 seconds later, and the bleeding quickly subsided.

      In a hospital, an OBGYN may have still gone in and "explored" the Uterus to look for tears after the placenta was delivered, causing much more trauma. And I would have supported the OBGYN in doing so too, because I wouldn't have had as long and as trusting a relationship with a Dr. I barely knew as I did with our Midwife, who we had spent 40 hours with over the course of the previous 9 months.

      Home birth is not for everybody. You take on a lot of responsibility giving birth to a baby at home. You have to be prepared. But it's truly a wonderful thing to spend the first seconds, minutes, and hours with your new baby in the comfort of your own home. To have privacy, and peace. To deal with the pain by retreating into oneself, as my Wife did, rather than through the brute force of drugs. My Wife doesn't even describe the experience as painful, just laborious.

      In my opinion, for better or worse, pregnancy is more akin to weather than climate. If you make decisions based on the "climate" of home vs. hospital birth, you're liable to end up wearing a wetsuit in the desert. You need to understand the climate as broad framing for your decision. But climate is a terrible predictor for your local conditions, so don't forget to look out your window and reason about your own circumstances.

    3. Also, you have to consider the case where someone has an actual bad idea and it's up to the doctor to convince them it is not in their best interest.

      "I'm only eating raw organic Kale and drinking rain water for this pregnancy, because I read on the internet that it is how cavemen had children and their children were strong and healthy and I don't want to impart the toxins from our modern food into my child."

      And then they get all butthurt when the doctor tries to explain that its not a good idea.

    4. c9r says:

      Thanks for the response, @CCProf. The midwife did immediately inspect the placenta to look for missing tissue. I acknowledge that things might have turned out quite differently had the placenta not been in tact. And I appreciate you clarifying what the hospital procedures might have been like

      Having watched my father die of cancer, and after watching my Mother-in-Law whither away to cancer while my Wife and I cared for her (she died 1 year and 1 week before my daughter was born, and yes she was treated), my Wife and I made a conscious decision to make choices based on how we want to live, rather than by how we might die. If my Wife had bled out during childbirth, it would have been the worst thing that ever happened to me. And I no doubt would have forever questioned the avoidability of it. But it was our decision; we made it together. And we were informed.

      The pregnancy was the most relaxed and wonderful time we had ever experienced. I know several people who were constantly stressed, and frankly terrified, while pregnant. The trick of course is to strike the right balance between living the way that makes you happy, and not dying too soon.

      I have never feigned to do everything possible to stay alive, only what's reasonable by my own definition. And in the gap between what's possible and what's reasonable lies risk, and also happiness.

      A key part of the "training" with our Midwife was discussing when and how to transfer to a hospital. Our strategy was always one of appropriate escalation. We were lucky to have a Midwife with 35 years experience successfully making difficult calls. The care was excellent. The experience was happy. And the outcome was good. If it had gone badly, we would have been at the hospital in 10 minutes. That might have been too late, or it might not have. I'm thankful that we had a choice between a good midwife and a good hospital. I hope to continue to have the option of both, and the hegemony of neither.

    5. @daneel I think this is a good thing to bring up. Because it's not just doctors who can end up pressuring people into things they don't want and making them feel horrible. Like the doctors, lactation consultants, midwives, and doulas (and random friends and family) can have the best intentions and still end up creating bad situations where the woman giving birth doesn't feel like her circumstances and self are respected.

    Continue the discussion bbs.boingboing.net

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