REMODELING of Uteroplacental vasculature conves -

Remodeling conves narrow-lumen, muscular spiral aeries into dilated, low-resistance uteroplacental vessels Uteroplacental vasculature development proceeds in two waves or stages. The first wave occurs before 12 weeks post feilization and consists of invasion and modification of spiral aeries up to the border between the decidua and myometrium. The second wave is between 12 and 16 weeks and involves some invasion of the intramyometrial segments of spiral aeries.