Episode Summary
Executive Summary: Russ Roberts and Emily Oster discuss Expecting Better, arguing that pregnancy decisions should be based on data, causation, and tradeoffs rather than folklore or blanket prohibitions. They examine caffeine, alcohol, smoking, food restrictions, cats, home birth, and delivery interventions, emphasizing that risk varies by magnitude and individual context. The conversation also reflects on econometric uncertainty and Oster’s willingness to revise conclusions when better evidence emerges.
Main Topics: Evidence-based pregnancy decisions: Oster explains her frustration that doctors often offered rules without the underlying data, pushing pregnant women to make informed choices using evidence and judgment. Causation vs. correlation in pregnancy studies: The discussion centers on why observational studies can mislead, especially when third factors like nausea, age, or self-selection drive apparent associations. Caffeine and alcohol moderation: They review evidence suggesting moderate caffeine is likely safe and that small amounts of alcohol may not show harm in available studies, while excess alcohol is clearly dangerous. Food safety, listeria, and arbitrary-sounding restrictions: Oster argues that many food warnings are not equally justified; some risks are real, but the likelihood of avoiding listeria by avoiding certain foods may be very small. Smoking, birth weight, and randomized evidence: Unlike many pregnancy topics, smoking has stronger causal evidence because quit-intervention trials show clear benefits, especially improved birth weight. Labor, delivery, and patient advocacy: They discuss epidurals, C-sections, doulas, and the power imbalance in childbirth, emphasizing the value of support and pre-planned preferences. How economists should think about medical evidence: The conversation broadens to Oster’s earlier work on hepatitis B and sex ratios and to the broader challenge of drawing policy conclusions from imperfect evidence.
Key Arguments: Pregnant women need hard numbers and tradeoffs, not just reassurance or rules; decision-making under uncertainty is unavoidable. Observational studies in pregnancy are often confounded by factors like nausea, age, and self-selection, so apparent correlations may not be causal. For caffeine, evidence supports that up to about 200 mg/day is not associated with increased miscarriage risk, while very high intake may be harmful. For alcohol, the strongest evidence shows danger from heavy or binge drinking, but available studies do not show clear harm from occasional moderate drinking. Smoking is different because randomized quit-support studies show that reducing smoking improves infant birth weight and related outcomes. Many pregnancy food restrictions are only loosely connected to real risk; avoiding certain foods may change listeria risk far less than people assume. A doula or informed advocate can reduce unnecessary interventions because labor patients often cannot push back effectively in the moment. Economists can contribute usefully because the central question is causal inference, not clinical delivery care. Oster’s earlier hepatitis B hypothesis was overturned by better data, illustrating why scientists should be willing to revise conclusions when evidence improves.
Data Points: Caffeine threshold: 200 milligrams/day - Oster cites evidence that up to this level, about two 8-ounce cups of coffee, appears not to increase miscarriage risk. Coffee consumption: 3-4 cups/day - Evidence is mixed in the intermediate range; more than a little may be unclear even if very high intake looks risky. Labor length effect of epidural: About 15 minutes - Randomized trials suggest epidurals slightly lengthen labor, but by a small amount. Alcohol moderation prevalence among obstetricians: About 40% - Russ cites Oster noting that many obstetricians consider some moderate alcohol intake acceptable. Example drinking pattern: Half a glass to one glass, 3-4 times per week - Oster describes her own moderate alcohol consumption during pregnancy after reviewing the evidence. Pregnancy book limit: Stops at delivery room - Oster notes the book does not cover breastfeeding or post-delivery dietary questions. Birth weight cutoff: 2,500 grams - Discussed as the rough cutoff for low birth weight; very low birth weight is associated with more problems. Hepatitis B estimate: As much as 60% - Oster recalls her earlier speculative estimate that hepatitis B might explain a large share of male-biased sex ratios in some regions, later disproven.
Pivotal Quotes: "Are you kidding? Like you have to make these decisions. As opposed to what?" — Emily Oster: Oster rejects the idea that pregnant women can avoid decision-making by deferring entirely to authority or folklore. "Good news, ladies. If you are nauseous, you are less likely to miscarry." — Russ Roberts: Roberts summarizes Oster’s explanation that nausea is a marker of a healthy pregnancy and also a confounder in caffeine studies. "I think we have to recognize that by not all living on a rural farm in Finland away from all motor vehicle transportation and only breathing healthy Finnish air, we are all putting our babies at risk." — Russ Roberts: Roberts broadens the point to everyday risk and the impossibility of total safety in modern life.
Implications: Listeners should expect more nuance and fewer absolute rules in pregnancy guidance. The episode argues for evidence literacy, shared decision-making, and humility about medical certainty—especially where observational data can mislead and personal tradeoffs matter.
From the Episode
us not always make the best choices. And you know, like yesterday I was on the radio with a doctor who said, well, statistics is really hard. And so, you know, we don't think that we shouldn't really expect people to be making a lot of these decisions with data. And I think for me, it's like, are you kidding? Like, you have to make these decisions with data. Right. What is your other system? Like, what I only, this is the only system that we have. You know, there's no like secret other system. This is it. So we have folklore, superstition, some of which are. is true. Some of the folklore is true, obviously. But in general, people, data help. And I think you make an interesting point there when you say, when we talk about how people don't want the data themselves, then doctors, I think, sort of get in the habit of and enjoy telling people what to do as opposed to saying, well, you know, this is your call. You're going to have to think of it yourself. Yeah, and certainly not all. And so I think, you know, one of the things that is definitely true is there is variation across.
In addition, in the case of coffee, and this was in some sense the most interesting thing for me research-wise, there is also a problem with nausea. So if you are nauseous in early pregnancy, it's a very good sign about the health of the pregnancy. So women who are nauseous, like good news, ladies, if you're nauseous, you are less likely to miscarry. But women who are nauseous are also more likely to avoid coffee. So when you look at women and you see some of them drink a lot of coffee, Those women are also, on average, women who are less nauseous. And when you see that they then miscarry at higher rates, it may well be just that not being nauseous is a sign of miscarriage and caused them to avoid coffee, but or cause them to drink coffee rather, but it's not that the coffee caused the miscarriage. And I think that getting around that kind of challenge is very complicated. This is what is sometimes called spurious correlation. It's also what my friend and
Birth guys on one side and the non-home birth guys on the other side. And I, you know, I wouldn't do it. And I think we have to recognize that having a home birth has additional risks relative to a hospital birth. I think to not recognize that seems silly to me. Although I think, in fact, like done correctly, it may be that those risks are relatively small. And offset potentially for some people by 100 other things that are nice about home. Yeah. I mean, I have friends who have had their babies at home. Who said, like, this was great, and I understood that there was some risk, but for me, you know, there was a really big benefit. And I think, you know, I think that acknowledging that people may have different preferences, which take into account those risks and benefits, I think is very, very important. One of the advantages of the home birth, by the way, is the avoiding of many of the things that you talk about in the book where things were done to you or given to you, and I think this is true for every pregnant woman, that you might not have been so crazy about.
About EconTalk
EconTalk: Conversations for the Curious is an award-winning weekly podcast hosted by Russ Roberts of Shalem College in Jerusalem and Stanford's Hoover Institution. The eclectic guest list includes authors, doctors, psychologists, historians, philosophers, economists, and more. Learn how the health care system really works, the serenity that comes from humility, the challenge of interpreting data, how potato chips are made, what it's like to run an upscale Manhattan restaurant, what caused the...