What happens in pregnancy and the early stages of infancy can have a profound impact on child and adolescent development, and may even affect the health of individuals as adults. A growing understanding of which events may be most harmful for a growing fetus or newborn can lead to improvements in the health of babies, but it can also create quite a bit of fear and anxiety in expecting mothers and new parents. How do new parents sift through the many “dos and don’ts” that are thrown at them during pregnancy? What does the evidence base actually support? In previous podcast episodes, we discussed infertility (how to get pregnant) and maternal mortality (how to keep mothers safe during delivery); on this episode we focus on the health of the fetus and newborn baby. Bryan James and Hailey Banack chat with Robert Platt from McGill University about the latest in perinatal epidemiology, and why it is so hard to find answers to these questions using observational studies!