Placenta takes over function of corpus luteum for production of hormone at:
Placenta stas making estrogen, progesterone after 6 weeks Luteo-placental shift occurs from 6-9 weeks, this means that the placenta stas to TAKE OVER the function of corpus luteum of hormone production such that by 8-9 weeks, most of estrogen and progesterone in maternal circulation is placental in origin. The function of the corpus luteum begins to decline after 8 wk of pregnancy, but it persists throughout pregnancy.
8 weeks
12 weeks
18 weeks
24 weeks
Placenta - Types and their complications