Placental insufficiency is a complication of pregnancy in which the structures that help bring oxygen and nutrients to an unborn baby develop abnormally. This affects the growth of the unborn baby.

The placenta is the structure that brings oxygen and nutrients to a fetus,. It also helps gets rid of carbon dioxide and other wastes.

Certain conditions in the mother, such as high blood pressure, can contribute to problems in the placenta. In some cases, the placental membrane can break or leak, allowing fetal blood to mix with the mother's blood. This can be associated with problems such as Rh incompatibility, kidney disease, and diabetes.

Placental insufficiency also occurs if the placenta does not implant correctly onto the surface of the uterus, and can be caused by multiple pregnancies.