The placenta is an organ often neglected by surgical pathologists and clinicians alike. Placental diagnoses provide risk assessment for infant prognosis, recurrent risk for future pregnancies, and explanatory findings. There is widespread interest in placental diagnosis for the antenatal determinants of adult disease, inborn errors of metabolism, specific infections, malignancies, and assessing placental function in real time with the ultimate goal of affecting treatment. Due to the difficulties inherent in studying human gestation and gestational pathologies, much of what is known about the...