AUDIE CORNISH, HOST:
Let's say you've got a 6 month old baby - so cute.
(SOUNDBITE OF BABY BABBLING)
CORNISH: It's time for the baby to start eating solids. How do you do this? Well, you talk to your pediatrician, maybe your friends. Maybe you go on YouTube, watch some blogger videos.
(SOUNDBITE OF YOUTUBE VIDEO)
UNIDENTIFIED YOUTUBER #1: ...Speaking to my pediatrician and doing some of my own research, I figured that this Gerber rice cereal was going to be the best thing to introduce to her.
CORNISH: Pretty quickly, you're going to get really confused.
(SOUNDBITE OF YOUTUBE VIDEO)
UNIDENTIFIED YOUTUBER #2: But with my research and also talking to my own doctor, I've decided that I'm not going to be using rice cereal. It could be the leading cause as to why there is child obesity.
CORNISH: Enter economist Emily Oster and her new book. It's called "Cribsheet: A Data-Driven Guide To Better, More Relaxed Parenting, From Birth To Preschool." NPR's Selena Simmons-Duffin talked to Oster for some advice on sifting through all the advice.
SELENA SIMMONS-DUFFIN, BYLINE: Did you catch that? Two bloggers did research and talked to their doctors and came out with opposite conclusions on rice cereal.
EMILY OSTER: It turns out, there isn't any evidence to suggest that that is a particularly important way to introduce foods or not.
SIMMONS-DUFFIN: Emily Oster says the answer to this one: you do you. Keep the food mushy, and don't stress about it too much. She says, studies show and researchers find can mean a range of things, from really rigorous, convincing studies that came to a strong conclusion to some scientists wrote up a few case studies.
OSTER: What I do in the book and what I do in my job is actually try to comb through these type of studies and find out what the best information is.
SIMMONS-DUFFIN: That job is professor of economics at Brown University. This is also what Oster did with pregnancy in her very popular first book, "Expecting Better."
OSTER: So then you can kind of make these choices having the best information, not just the first thing that comes up when you Google it at 3 o'clock in the morning.
SIMMONS-DUFFIN: Here are a couple parenting takeaways from the new book: you don't need to wait three weeks after birth to give a pacifier or a bottle; nipple confusion is not a thing. Spanking is harmful and doesn't work. Breastfeeding does not help mom lose weight.
OSTER: No. No, it does not help you. I mean, I think it does burn calories. But also, you tend to eat more. Yeah.
SIMMONS-DUFFIN: I've been living my life wrong for the last couple of years.
A lot of the other takeaways in the book are kind of nuanced. One reason for that is designing a good study of the risks and benefits of a parenting decision is really hard. Take for example, Chapter 4, titled "Breast Is Best? Breast Is Better? Breast Is About The Same?"
OSTER: Most of the studies on this are done by comparing the kids whose moms breastfeed to the kids whose moms don't. The issue with that is that the kinds of moms who breastfeed are different than the moms who don't - on average. So in the U.S. in particular, moms who breastfeed tend to be better educated, higher income, more likely to be married.
SIMMONS-DUFFIN: Let's say you want to find out the impact of breastfeeding and not these other differences on things like IQ and obesity.
OSTER: When we sort of narrow in on some studies that are better - like, for example, studies that compare siblings, where one sibling is breastfed and one kid is not, those studies do not show the same kinds of impacts on long-term things like obesity or IQ.
SIMMONS-DUFFIN: For the record, Oster found there are some health benefits to breastfeeding. But they're more limited than the hype. So you've made a decision about breast or bottle. There are so many other ones to make. What about baby nap schedules and the financial impact of choosing a nanny or day care or staying home - or how to potty train? As an economist, Oster advocates for taking some of the angst out of it. Here's her decision-making method.
OSTER: Step 1 is to kind of really figure out what the best evidence says about the choice, so randomized is a good signal. I think we're often looking for sample size. So if the study is 42 people, that's not as good as if it is 700,000 people.
SIMMONS-DUFFIN: Step 2, she says, is figure out your preference and give that real weight. When she first brought her baby daughter home, she knew the American Academy of Pediatrics recommended your baby sleep in your room for the whole first year.
OSTER: My husband, he did one day with our older daughter. He was like, I can't believe it's making those noises.
SIMMONS-DUFFIN: It's true. Newborns make weird grunting sounds.
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OSTER: He just couldn't do it. Like, he...
OSTER: ...Wouldn't sleep.
SIMMONS-DUFFIN: So that was not the AAP-recommended one year.
OSTER: No, that was not the AAP-recommended one year for us, no.
SIMMONS-DUFFIN: With "Cribsheet," Emily Oster is doing her bit to make a world in which parents are less confused, more confident in their choices and less judgmental of parents who make different choices.
OSTER: Yes, that is exactly the world I would like to achieve.
SIMMONS-DUFFIN: In other words, you do you. Selena Simmons-Duffin, NPR News.
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