The role of the placenta in fetal development is being seriously under-appreciated according to scientists. A team studied 103 mutations linked to prenatal death in mice and showed that almost 70 percent affect the placenta. The team also found that some placenta defects could be directly linked to the cause of death. As such, a significant number of prenatal deaths may be due to the placenta, not just the embryo.

https://www.sciencedaily.com/releases/2018/03/180314144737.htm