The placenta, which is a regulator organ for many metabolic activities between mother and fetus, is critical in influencing the outcome of pregnancy. Therefore, fetal growth is directly related to the placental development. Placental development depends on the coordinated action of trophoblast proliferation, differentiation and invasion. Studies on cell cycle related proteins that control these events are limited. Abnormal placental development is linked to various pregnancy pathologies such as preeclampsia, intrauterine growth restriction, diabetes mellitus and gestational trophoblastic diseases. The cell cycle mechanism of human placenta should be well understood for a healthy pregnancy outcome. Moreover, how cell cycle related proteins that control placental development are affected in pregnancy pathologies is not fully understood yet. Therefore, the aim of this review is to address the currently available knowledge on cell cycle regulatory proteins involved in human placental development and on the expression differences of these proteins in pathological placentas.