Emily Oster, bestselling author and economist, joins the show to discuss data-driven parenting approaches. Her books Expecting Better and Crib Sheet have sparked global conversations about what research actually reveals versus popular parenting advice.

The conversation covers the full parenting journey from conception through toddlerhood, examining evidence on fertility, pregnancy restrictions, breastfeeding, sleep training, and childhood development. Oster emphasizes distinguishing between correlation and causation in parenting research.

Key topics include debunking pregnancy myths, understanding the limited control parents have over outcomes, and preparing for parenting as a complex "group project" that requires planning and realistic expectations about what data can and cannot tell us.

Getting Pregnant: What You Can Actually Control

Fertility control is more limited than people think, with expensive prenatal vitamins and fertility supplements often being marketing that preys on anxiety about "getting it right"

The controllable factors for conception are straightforward: track ovulation for proper timing, ensure sperm quality through testing, avoid smoking and heavy drinking, and reduce heat exposure to testicles

Even with perfect execution, there's only about a 30% chance of pregnancy each month, making the process "just a dice roll" after addressing the controllable factors

Pregnancy Myths Debunked by Data

Expecting Better revealed that bed rest, commonly prescribed for pregnancy complications, shows "almost no condition for which bed rest is helpful and many conditions for which it's actually harmful" - Emily

Most food restrictions during pregnancy lack evidence: occasional wine (especially later trimesters), moderate coffee consumption (1-2 cups daily), and sushi are all supported by data as safe

Pregnant women worry excessively about minimal exposures like touching pesticide-treated lawns, when "there is no mechanism whereby touching a lawn, even recently treated with pesticides and then washing your hands would actually impact your pregnancy" - Emily

The focus should shift from obsessing over food choices to preparing marriages and home life for "introducing a new person, somebody who requires all of your time and money" in a challenging group project environment

Breastfeeding vs Formula: What the Evidence Shows

Crib Sheet addresses the breastfeeding pressure that was "really harming" families, with fathers writing concerned emails about wives being depressed over breastfeeding struggles

Breastfeeding shows small short-term benefits like lower gastro-intestinal illness risk, but long-term claims about intelligence and health are "all correlation, not causation" - Emily

When comparing siblings where one was breastfed and one wasn't, "you see no effect" on IQ, indicating initial differences reflect maternal characteristics rather than breast milk benefits

Both options are expensive: "people will tell you breastfeeding is free. I'm sorry, does my time have no value?" - Emily, emphasizing that formula costs money while breastfeeding costs time

Sleep Training: Safety and Effectiveness

Sleep training involving some crying doesn't cause attachment problems according to "a lot of data including randomized data" and "community based data" showing it's not damaging to children

The attachment theory concerns stem from observations of severely neglected children in Romanian orphanages, which differs drastically from "crying for even a pretty long period of time for a few nights in the context of an otherwise loving and stable household"

Sleep training effectiveness requires parental commitment - "it doesn't work well if you are not ready to do it" because consistency is crucial and ambivalent parents won't maintain the approach

Two sustainable approaches exist: sleep training for independent sleep or co-sleeping, but the unsustainable middle ground of "waking up every ninety minutes and I have to go put them back to sleep" doesn't work for most families

Screen Time and Social Media: Correlation vs Causation

Screen time research represents "perhaps the best example of correlation is not causation in parenting" with studies comparing vastly different households that differ in many ways beyond screen exposure

The American Academy of Pediatrics has "recently dialed back their screen time restrictions to a set of guidelines that more or less say just kind of think about it a bit more"

Social media for children requires scaffolding like learning to drive: "you don't just hand them the keys and say enjoy. You like teach them" and maintain willingness to remove access when needed

The key question isn't whether screens are good or bad, but what activities they're displacing - if replacing sleep that's problematic, but if enabling family dinner preparation, that could be beneficial

Vaccines and Medical Decisions

Childhood vaccines on the standard schedule "have been really safe and effective" for decades, with measles cases spiking dramatically due to vaccine hesitancy - "more measles cases in a single week in January 2026 than all but a small handful of years over the past two decades"

The current vaccine conversation conflates reasonable COVID vaccine discussions with essential childhood vaccines: "kids are going to die of measles who didn't need to die of measles"

ADHD medication may represent over-medication, particularly for younger kindergarten students who struggle with sitting still due to "age appropriate behavior" being medicalized in school settings