Multiple pregnancy in human is not a physiological event because the anatomy of the human uterus is designed to harbour only one fetus at a time.
Placenta of biamnial biplacental twins: Biamnial bichorial placenta, twins, Macro, autopsy (73279)
Twins and bichorial biamnial placenta: Placenta, twins, Macro, autopsy (73974)
Bichorial biamnial placenta: Placenta, bichoriadal biamnial twins, Macro, autopsy (73996)
Fetal death in multiple pregnancy:
Suprisingly many pregnancies begin as multiple, but one fetus usually dies sooner than multiple gravidity is recognized (before 10th w.g):