“…For example, the micronutrient vitamin D is very important for maternal and fetal health, affecting the immune and musculoskeletal systems, neurodevelopment, and hormones [112, 113, 114, 115, 116] (see Figure 1). Abnormal vitamin D levels can lead to gestational diabetes mellitus, preterm delivery, frequent miscarriages, adipogenesis, pre-eclampsia, obstructed labor, Cesarean sections, reduced weight at birth, respiratory issues, postpartum depression, and autism [112]. If we can identify the known unknowns in prenatal nutrition, even just with regard to the role of vitamin D, then we can look to other fields to help us answer the questions raised, and thereby avoid the additional risks faced when studying pregnant women and their children.…”