Evidence-based pregnancy should be about decisions, not hard rules


The insight of the connection between coffee and nausea is very good, but I think there is room for a real physical explanation for why less caffeine might be safer. We build up a very strong “tolerance” to caffeine and anyone who takes in a lot of caffeine can tell you that less-than-what-you-are-used-to is a very real thing with profound effects on your body. It is not implausible that the important thing is that you cut back a bit from wherever you were - or that the important thing is that you don’t increase the amount you are taking.

Still, this was a great article. More sanity around drinking and weight gain during pregnancy would be extremely welcome.

The net takeaway is kind of depressing. Yes, if you (like this author) are one of the few who has both the time and the chops to do a review of the primary literature on choices that are important to you, you can make a good, informed decision. Otherwise, you’re stuck with faddish and quasipuritanical advice.

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This is slightly tangential, but it was interesting what she said about weight gain. I was surprised when my sister described the check ups she has with her young daughter at the pediatrician. Any time her daughter is even slightly off the median for height and weight, my sister gets a talking to. And that’s always, because the bell curve for height and weight is just that–a curve. It’s not a mile-high spike right at the median with only 2 or 3 kids on either tail. I can see why there might be some concern if a kid is three standard devs out–he or she might be fine, but it’s worth looking into problems that might be causing the wide variation–but it kind of confused me that the doctor didn’t seem to understand that a large population actually varies, and not all, or even most, variation is a sign for OMG PANIC TESTS NOW!


Two things on this:

  1. The absence of really good evidence regarding some of these issues does not necessarily indicate that people are superstitious or don’t believe in science. Rather, it may be difficult or impossible to ethically conduct research on those subjects. To pick an extreme example, there is no peer-reviewed journal article that reports a statistically significant showing of harm resulting from punching babies in the face. I would not infer from the absence of such an article that anyone who won’t punch a baby in the face doesn’t believe in science.

  2. Deli meats: for f’s sake, don’t eat them while you’re pregnant. You shouldn’t really eat them anyway. A 1 in 10,000 risk does not seem large, but it is about 20 times larger than the risk of skydiving, and skydiving is a lot more thrilling than lunchmeat.

Well, yes, a knee-jerk reaction of “OMG, the kid is fat” is stupid … but at the same time, childhood (and adult) obesity is a huge issue in this country. And staying thin is FAR easier than losing weight once you’ve packed on the pounds. I see kids in my children’s school that are already VERY overweight for their size and I keep thinking about how hard it will be for them to lose that weight someday if they want to.

If your pediatrician can’t sound the warning bell on a possible weight issue early, who can?

Anecdotally … head to your nearest Wal-Mart. There are a LOT of parents of kids there that need to be told VERY emphatically to worry about their child’s weight.

Or, you just read the books that condense all that research, tell you what’s actually going on, and leave you to make your own choices. Those books do exist. And those doctors (the ones that communicate on this same level) do exist. Thankfully.

Substitute “medicine” for “pregnancy,” and you’ve got it. It’s not just a pregnancy problem.

It’s more of an issue for pregnancy than a lot of other things, largely because we don’t have good data (as someone else pointed out, it’s hard to do actual clinical trials on most of this stuff) and because there is a lot more moralizing associated with pregnancy than with, say, gall bladder surgery.


I also wonder how much of it is “break it down into simple rules because my patient won’t listen to anything more complex.”

I remember when my wife was pregnant and her doctor started telling her things in very simple terms. My wife, who is, I think, very smart, started asking some very good questions that showed she understood AND had done some homework. The doctor, bless her, gave a little pause and then totally changed the level of discussion.

From then on, the doctor was very careful to lay out options and reasons for everything so that my wife and I could make what we felt were informed decisions.


But here’s the thing, just because you aren’t in that 25-35 pound weight gain range doesn’t mean your kid is going to come out obese, or have problems with obesity, or not be able to lose weight later if they want to.

I’m eating well (and not “eating for two”). I do 2 miles on the elliptical machine at least 3 days a week (usually more). I’m almost to the 35 pound limit with almost two months left to go. My doctor asked about what I’m eating. But he doesn’t moralize or tell me that I’m doing anything horrible to my kid, because I’m not. And he says that the 25-35 pound thing doesn’t necessarily reflect what’s normal/healthy for everybody. It’s a generalized, fuzzy guideline that’s meant to make it clear that, hey, you shouldn’t eat twice as much as you normally do or subsist on ice cream. But it’s not a hard rule where, if you pass this point, OMG, your child is doomed to a life of being a fatty fatty fat fat.

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Yes, but the no-drinking-coffee-or-alcohol-during pregnancy rule is something that was created just a few decades ago. It’s by no means some obvious connection that we all intuitively know even if dumb ol’ science hasn’t proved it yet. Many of our parents and our ancestors drank during pregnancy.

Then came the scares, based on small samples and binge-drinkers, and it became something that “everyone knows.”

Then better studies came along, based on many of thousands of individuals, and found that the earlier evidence was weak at best, and possibly quite wrong for most cases.

If you read the article, you’d find that there are quite good studies on the effects of drinking alcohol on pregnancy, contrary to your argument.

Again, that’s based on your own gut feeling, not the studies. From the article: “My best guess was that avoiding sliced ham would lower my risk of listeria from 1 in 8,333 to 1 in 8,255.

That’s not a huge decrease in risk at all.


The pregnancy ‘information’ frenzy is a racket, as is the ‘baby products’ insanity.

Our first child we drove ourselves insane worrying about foods, the birth, various stages of pregnancy and everything else. The single only use for the book 'What to expect when…" should be as firewood. Judgemental, puritanical lunacy preying on nervous new moms and (to a lesser extent) dads. Burn the fucking thing.

A first pregnancy is a scary thing. All kinds of physical changes are happening, hormones are flowing, your whole life is changing. And to top it off, there is a big scary birth coming at the end of it, which is a source for a lot of fear and nervousness, and unfortunately every damn person on the planet has an opinion about how you should or should not experience a birth.

Here in BC we are very lucky - we have a large, very well trained and highly professional bunch of excellent midwives whose only job is to deal with pregnancies and birth. And they are awesome. My understanding is that it is not universal, and that there are also uncertified, untrained people out there masquerading as midwives - not awesome.

The funny thing about our first ‘birth’ is that we spent all our time obsessing about the birth, planning it, getting things ready. Then it happened. And we realized we had spent relatively little time or energy thinking about the next day, when there is actually a real human person in your house who isn’t going home somewhere else, is totally dependent on you for literally everything, and has absolutely no skills or communications capacity. It is absolutely overwhelming. Also awesome, but very much a shock the first time around.


If I may, I’d classify as one of the more intelligent patients your doctor has, too. He can have that conversation with you.

It may be my techsupport background cynicism showing … but there are a LOT of (willfully) stupid people in the world and a fuzzy rule just won’t work. They want “Do X and you are fine” type rules.

It may seem like it, but I beg to disagree. My mom was head of nursing at a hospital before retiring, and she constantly lamented what you’re talking about. And she was cardiac rehab. They’d run into people who had vascular differences, different family histories, and all anyone did was play the odds. Even if there was an obvious piece of investigation that could reveal what happened, the doctors didn’t listen if a few symptoms fit their theories.

Another anecdote: I broke my arm last year in a bike fall. The fall was very odd, it appears my bike wheel locked up, and I should have done what was called a “highsider”, but I didn’t. Anyway, the doctors were convinced that I threw my arm out and that’s how it broke, and multiple doctors ignored my information once that “theory” was in their heads. It wasn’t until I protested multiple times (at ER and at a separate doctor) that I got them to look at my elbow (which they ignored saying it was just my wrist), and it turned out I had a completely different break than they assumed. But because they had decided “bike accident = arm out = wrist impact”, my protestations to show a rotational fracture were ignored.

Point is, I think with our sorry state of medical care & pricing, it’s far easier to just play the symptoms and not do the follow up work to find out what’s REALLY going on. If N% of the cases say something (your child is going to be overweight, your cancer will take you out in 6 months and there’s no point in going further), then that’s the easier & cheaper thing to do. Triage, basically. Or, as my favorite bit in Meaning of Life put it:

“What do I do?”
“Nothing dear, YOU’RE NOT QUALIFIED.”

The problem is that many of these rules aren’t even right. You can argue for “Just don’t drink” because it’s easier to follow than “only have a drink every now and then” (though I don’t even think this is true for most people), but “Don’t gain 36 pounds” is just absurd. The weight ranges they use don’t even vary by the size of the mother. If you are six feet tall and weigh 200 pounds you are supposed to gain the same amount of weight as a 4’10" woman who weighs 85 pounds. If your baby is over 10 pounds then they’ve got to test for diabetes, never mind that her father was over 10 pounds more than thirty years ago when baby weights were noticeably smaller on average.

I did tech support too, but unlike electronics, women’s bodies during pregnancy are extremely idiosyncratic. Guidance is good, but having one strict set of rules for everyone is insane.


Your overreaction and clear judgement of fat people is not helpful.

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I agree about a pediatrician being a good gatekeeper for that sort of thing, but the kind of differences I’m talking about are really very slight. My niece was somewhere in between the 50th and 60th percentiles for weight, which got my sister a warning, and then she shot up a few inches in height without putting much weight on, which put her in between the 40th and 50th percentiles, which earned her another warning. Now, my sister used to be a research biologist, so she knows what these statistics mean, but she still reported them to me with a sense of worry and defeat. I can’t imagine what someone who’s less math-literate would feel about that, and it still seems completely ridiculous to start rattling a parent when a kid is otherwise healthy AND less than a standard dev away from what they determine to be the ideal weight.

To be fair, I’m biased, because when my cholesterol hit 205 but I was otherwise healthy by the normal metrics, my doctor scolded me like I was eating nothing but chocolates dipped in rich, creamery butter. I hate scoldy doctors. :frowning:

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  1. If there is really good evidence by all means people should rely on that. My point is that in the absence of such evidence it makes sense to rely on your priors.

  2. I don’t see the basis for Oster’s calculation in her article. About a thousand pregnant women contract listeriosis each year, it’s very serious, and deli meats are a significant source of listeria. Is the gross risk small? Yes. Should a pregnant woman who was totally craving a ham and cheese sandwich feel guilty about having had one? No. Should pregnant women in general avoid deli meats? Without question.

Another possibly-unpopular-in-a-nerdy-science-blog-community-like-boing-boing approach to this topic is simply this: don’t bother reading any of it, relax, and just figure it out as you go. I know in this information-driven age such a suggestion seems like madness, but if you take a step back, you’ll realize that the birth process has been going on for zillions of years. It’s a pretty well-refined thing that requires very little work on our part from a decision-making point of view. You can read a hundred books every week or none at all, and the end result will be the same. I would argue the end result is actually better when you are in the womb of a relaxed, stress-free mother for 9 months than when you’ve got a mom who is spending a lot of mental energy over whether she’s doing the right thing, eating the right thing, getting enough X or too much Y.

I’m not advocating ignorance, I’m advocating knowing when to say when (when it comes to information overload.) Given that scientific research in this area is constantly debunking the previous generation of scientific research in this area, I don’t see much use in trying to keep up with it. Our kids are going to think we were out of our minds, giving birth like we did, just as we think this of our parents: feeding us baby formula, smoking and drinking while pregnant, etc. I can’t wait to find out all the shit we’ve been doing wrong.

Seriously, every pregnancy is different. Every body is different… and for the most part, we’re a lot more resilient and flexible than we give ourselves credit for. People with atrociously unhealthy lifestyles are still able to produce perfectly healthy babies. I have so many friends that are constantly second-guessing themselves because of research they’ve read and heard, and it’s doing no one any good. Whoever popularized the notion of viewing babies via percentiles should be shot- it’s been nothing but destructive in our modern society. Moms are dealing with enough shit as it is!