non-placental
/ˌnɒnpləˈsɛntl/adjective
Not relating to or derived from the placenta; (Zoology ) designating a mammal characterized by the lack of a placenta in the female during gestation (i.e. a monotreme or a marsupial).
Origin
Mid 19th century; earliest use found in Philosophical Transactions of the Royal Society of London. From non- + placental.