Emily Oster Explains What The Science *Really* Says About All Those Parenting Choices

Emily Oster wants to talk about vaginal tearing. Also, sex after childbirth, postpartum depression, nipple shields, and the relationship tension that often comes with a new baby. That’s all in addition the barrage of other questions that can overwhelm any new parent – from breastfeeding and sleep, vaccines and childcare, screen time and discipline. These topics and more are covered in her new book, Cribsheet: A Data-Driven Guide To Better, More Relaxed Parenting, From Birth To Preschool (Penguin).

New parenthood is joyful, for sure, but it’s also comes with surprises, some of them painful and anxiety-inducing. I remember well the pain of engorged breasts and cracked nipples and the exhaustion from endless hours bouncing on a yoga ball to soothe our fussy newborn. And then there are the decisions: every day, new choices to make, all in the fog of sleep deprivation. “With your first kid, everything is like a fire hose, at least it was for me,” Oster says.

Me too, Emily, me too.

My professional training is as a scientist, and when I realized that maternal intuition was inadequate against this fire hose of parenting decisions, I looked to research for guidance. Finding there wasn’t a good parenting book taking this approach, I wrote my own (The Science of Mom, Johns Hopkins University Press), and feedback from readers told me I wasn’t alone in wanting more science to inform my decisions. In this regard, I think parents have been underestimated for too long, and I’m happy to see Oster’s latest contribution to this genre of evidence-based parenting books. The more we can move away from ideology and prescriptive advice towards understanding the evidence and empowering parents to make the best decisions for their families, the better.

The data is the same for us all, but the decisions are yours alone.

Oster, a professor of economics at Brown University, approaches parenting decisions by weighing the evidence that exists but also incorporating it into a framework that considers the “constraints” unique to each family, like time, money, energy, and personal preferences. “The data is the same for us all, but the decisions are yours alone,” she writes.

She took a similar approach in her first book, Expecting Better: Why The Conventional Pregnancy Wisdom Is Wrong — And What You Really Need To Know. In that book, Oster told me, the central tension was between her — an economist frustrated with all the rules of pregnancy, some of which weren’t backed with good data — and the “medical establishment” that handed down those mandates without citing evidence. In Cribsheet, Oster has lost the adversarial tone towards medicine, and most pediatricians will likely agree with her balanced presentation of the data. “I think really the central tension in this book is between parents and other parents,” she says.

It’s about the way we judge ourselves and others, or feel that we’re being judged for our choices.

Oster says it’s natural for new parents to want to make all the right decisions for their baby and then to assume that if a choice worked well for them, it must have been the right one, and that therefore others should do the same. And because there’s plenty of conflicting studies out there, you can always find one or two that support your decision. But this approach is based on the false premise that there is a “best” choice for every decision, which just feeds modern parenting controversies about things like breastfeeding, co-sleeping, sleep training, childcare, and screen time.

A better approach is to look at the evidence as a whole, focusing on the highest quality studies and acknowledging the limitations of lower quality ones. This is how Oster frames the discussion, and you’ll find the same general approach in my book. In Cribsheet, you’ll learn that there are a few parenting choices where the evidence is quite clear. For example, the benefits of vaccinating your kid far outweigh the minuscule risks; it’s safest for babies to sleep on their backs; and calm and consistent discipline is effective, whereas spanking can result in worse behavior. But most decisions are less clear, usually because the evidence is from lower quality studies that are harder to interpret, and because there are trade-offs whatever your choice.

For example, most of the studies that look at effects of breastfeeding or formula-feeding are observational in design. They observe babies who were breastfed or formula-fed and see how often they get sick or how they grow. But this type of study has a major limitation: mothers who choose to breastfeed, on average, tend to be more privileged in lots of ways, with more education, higher income, more maternity leave, better health, and less stress related to socioeconomic hardship or racism. These studies can never fully tease apart whether something like higher IQ is caused by breast milk or the multitude of other factors intertwined with this single parenting choice. Focusing on the highest quality evidence, like that from randomized trials and twin studies, Oster concludes that there are some short-term benefits for the baby, like fewer gastrointestinal infections and lower risk of eczema, and the benefit of lower risk of breast cancer for mothers. However, many of the claimed benefits of breastfeeding, like making your kid smarter or healthier in the long-term just aren’t backed by good data.

Once you understand that evidence, you can weigh the benefits and costs for yourself, Oster says, and it’s OK to acknowledge that breastfeeding can also come with costs, like time spent pumping and, for some women, pain or discomfort with the process. On the other hand, many mothers enjoy breastfeeding and the opportunities for closeness that it brings, and that alone can be considered a major benefit.

The benefits of vaccinating your kid far outweigh the minuscule risks; it’s safest for babies to sleep on their backs; and calm and consistent discipline is effective, whereas spanking can result in worse behavior. But most decisions are less clear.

In another example, Oster dissects the evidence behind where your baby should sleep — in your room or a separate room. Room-sharing for the first year is recommended by the American Academy of Pediatrics to reduce the risk of SIDS, but Oster notes that the evidence to support this recommendation is weak, and studies also show that babies who sleep in their own room from an early age tend to sleep better in infancy and even as toddlers. Room-sharing is a trade-off, then; maybe there is a small safety benefit for the first few months of life, but if it compromises sleep for the family, the ripple effects of poor sleep are worth considering.

Oster covers many more topics in her book, and throughout, she encourages readers to step back and look at their decisions through a wide lens that incorporates the wellbeing of the entire family. As new parents, we can be so focused on the needs of our babies that we can forget our own needs and preferences, and in the long-run, this doesn’t help us or our babies.

Oster’s hope for her readers? “That people take away confidence in their ability to make these decisions for themselves, because I think so much of what makes parenting happy and bearable is feeling like you made the right choice for you, and for your kids,” she says. With Cribsheet, Oster has given parents a helpful guide to navigating these choices in their own way.

Cribsheet is available on April 23 from Penguin Random House.