Thursday 22 November 2012

Kid Sanity

Bryan Caplan tells us that because the return to parental input is low, we can all ease up on the parental production function. Parents agonise about whether they're doing enough; the ones who do so-agonise are usually doing far too much on any rational cost-benefit calculation. Conclusion? Spread the same amount of total effort over more kids. The reduction in average child quality really won't be that big and you'll be a lot happier in your old age.

But Bryan errs a bit. He neglects that we also could be putting too much effort into antenatal care. Sure sure, there's a big left tail that are screwing up horribly on that front. But that tail isn't reading economics blogs or parenting books written by economists. Instead, the folks who do read econ blogs are busily beating themselves up for having a bit of soft cheese or sneaking a sip of wine during pregnancy. If we are erring in making pregnancy far more costly for our wives than it really needs to be, then we're really screwing up: no matter how convinced we are about Bryan's arguments, if pregnancy is really unpleasant, that up-front cost can kill our future potential unrealised children.*

Emily Oster's forthcoming book then will be a beautiful complement to Bryan's work. Amazon should sell them as a bundle. Doctors, midwives, and right-thinking-tut-tutting-jerks give us all kinds of advice about what good people do. A lot of those really just seemed to be nonsense.

Take alcohol. When we were expecting, none of the advice on alcohol seemed to make sense. Sure, getting drunk seemed a really bad idea. But the dose always makes the poison. So I went and checked the literature and concluded that light drinking during pregnancy was effectively harmless. So Susan had the occasional glass of wine; we were also big fans of Harrington's SobeRing Thought - the low alcohol beer that local brewer Harrington's made for the Lord of the Rings.** And I blogged a bit on how the risks of alcohol during pregnancy seem overstated: if anything, public health folks' warnings that there's no safe level of drinking seem a noble lie intended to dissuade those pregnant women who'd otherwise drink a bottle of scotch in an evening.

If you can't have a glass of wine with dinner every other night during pregnancy, then pregnancy is less fun than it otherwise would be. And so the kind of people who listen to this kind of advice are having too few kids.

Oster seems to have been as annoyed as we were. But she's done something far more constructive about it - she's compiled the evidence for those of us who care about evidence. From the Amazon blurb:
When Oster was expecting her first child, she felt powerless to make the right decisions for her pregnancy. How doctors think and what patients need are two very different things. So Oster drew on her own experience and went in search of the real facts about pregnancy using an economist’s tools. Economics is not just a study of finance. It’s the science of determining value and making informed decisions. To make a good decision, you need to understand the information available to you and to know what it means to you as an individual.

Take alcohol. We all know that Americans are cautious about drinking during pregnancy. Official recommendations call for abstinence. But Oster argues that the medical research doesn’t support this; the vast majority of studies show no impact from an occasional drink. The few studies that do condemn light drinking are deeply flawed, including one in which the light drinkers were also heavy cocaine users.

Expecting Better overturns standard recommendations for alcohol, caffeine, sushi, bed rest, and induction while putting in context the blanket guidelines for fetal testing, weight gain, risks of pregnancy over the age of thirty-five, and nausea, among others.
The tut-tutters are doing real harm here. Lower decile groups hear the "drink nothing" warnings, dismiss them entirely as nonsense, and go on to drink way too much while pregnant, doing real harm. High decile groups hear the "drink nothing" warnings and, adding that to all the other advice they're given about all the other costly-and-useless rituals they must follow during pregnancy, rationally decide to have fewer kids. This is a bad equilibrium. Shame that Oster's book won't be out for another year - the current equilibrium is costly, and the faster we can start fixing it, the better.

* As clarification: there's some optimal number of kids that each couple will decide to have. If the actual cost of having one more kid is lower than the cost parents think they have to face, or the cost they mistakenly decide to impose upon themselves, then optimal family size is a bit larger than the deciding-couple thinks. The deadweight costs of kids who optimally would be born from the parents' perspective but aren't born because of parental cost misperceptions is the problem - I don't think I'm pushing into Parfit territory here. But the problem is my wording, now clarified. Thanks

** Yeastie Boys and Kelly Ryan brewed the beers in this year's Hobbit film.


  1. I think the soft cheese thing is a bit of an over-reaction. Overseas soft cheeses are often made with untreated milk, so the risk of harmful bacteria is relatively high. Here in NZ there are regulations requiring milk to be pasteurised prior to sale or use in the manufacture of cheeses and other dairy products. The link below is to a document from ESR in which it is noted that Listeria monocytogenes (one of the main concerns for pregnant women) is readily destroyed by pasteurisation, and that soft cheese samples made from treated milk in the USA tested negative for the presence of L. monocytogenes.
    It certainly doesn't hurt to be careful, but much like alcohol I suspect the occasional bit of brie or camembert is likely not to proove harmful.

  2. I suspect you're right; I've not canvassed that literature as much. Having some reasonable assessment of actual risks from sushi and cheese would be rather nice though.

  3. Are there any studies showing the impact that the 'tut-tutters' have on high decile couples 'size of family' decisions vs other factors such as financial and housing/vehicle choice impacts? Whilst I agree with the gist of the post I'm not sure that these rituals have a significant impact - from observation it appears that being pregnant opens a woman up to all sorts of unwanted life advice from strangers.

    Besides you're raising the child for around 17 years anyway, so if dodgy advice that impacts on your life for the first nine months is a major concern then you might be in the wrong game - as we all know unwanted advice doesn't stop when the kid pops out.

  4. It isn't the unwanted advice that I'm hypothesising about; it's that people take advice that lead them to impose too-high a cost on themselves. This one's a first-principles micro hypothesis: people respond to costs as they see them; when things are seen as more expensive, people choose less of the expensive thing.

  5. I suspect that women also breastfeed for a shorter time than they might otherwise, for similar reasons.

  6. Shorter? The social pressure seems to push entirely towards more breastfeeding; the evidence, as I understand it, is a bit mixed - all kinds of confounding with poorer country data where use of formula mixed with dirty water has unambiguously bad effects.

  7. Yes, the social pressure is for more breastfeeding, but it's also towards perfect eating and no drinking alcohol during breastfeeding as well, and women give up because they get tired of that.

  8. Erm, not meaning to be 'that guy' but the pitfalls of formula go beyond bad preparation, it damages gut flora and contributes to all kinds of problems; breastmilk has good stuff in it too including that which greatly improves the immune system. So while I'm sure it was a throwaway comment on your part it is wrong through and through.

    People being pushed into believing that formula isn't bad, its just that breastmilk is ideal, is one of the reasons why the breastfeeding rate drops significantly at 3 and 6 months, when ideally babies are breastfed for at least a year (if weaned prior to a year they need formula). There is a lot of social pressure around parenting issues and I do believe that you are on the right track of 'care less'- mostly because caring more makes people listen to inaccurate information....of which there is a lot...