“There are many big decisions: Should you breastfeed? Should you sleep train, and with what method? What about allergies? Some people say avoid peanuts, others say give them to your child as soon as possible—which is right? Should you vaccinate, and if so, when?”

Oster encapsulates the multitude of decisions that confront new parents, emphasizing the complexity and diversity of opinions surrounding crucial aspects of child-rearing. Oster reveals the conflicting advice parents often encounter when confronting major dilemmas, ranging from breastfeeding to sleep training, allergies, and vaccination. By posing questions, Oster introduces readers to the challenges of parenting decisions, which sets the stage for the evidence-based and pragmatic approach that she follows in the rest of the book.

“Circumcision is an optional procedure. It’s not common everywhere—for example, Europeans typically do not circumcise. It has historically been quite common in the US, although circumcision rates have declined some over time, from an estimated 65 percent of births in 1979 to 58 percent in 2010.”

Oster discusses the elective nature of circumcision, and sheds light on its cultural variability and historical prevalence. Oster underscores the regional distinctions, noting that while circumcision is not a common practice in Europe, it has historically been prevalent in the United States. The mention of a decline in circumcision rates from 65% in 1979 to 58% in 2010 suggests a shifting trend. Oster’s advocates for a structured decision-making process that involves weighing the medical, cultural, and personal aspects of circumcision, aligning with the overarching theme of The Value of Data in Parenting.

“You’ll also sometimes see swaddling discussed in connection with an increased risk of sudden infant death syndrome (SIDS). To the extent we have data, this concern does not seem valid, as long as you are putting the baby to sleep on its back (which you should do regardless). Infants who are put to sleep on their stomach and are swaddled are at an increased risk of SIDS relative to those put to sleep on their stomach alone.”

Oster addresses the controversial topic of swaddling in connection with the risk of SIDS. Oster refers to the existing data to debunk concerns related to swaddling and its association with SIDS, emphasizing that the critical factor in SIDS prevention is placing the baby to sleep on its back, a practice widely recommended.