PROGESTERONE
Progesterone is a steroid hormone produced after ovulation by the luteal cells of
the corpus luteum to induce endometrial secretory changes favorable for
blastocyst implantation. It is initially produced exclusively by the corpus luteum
for up to 6–7 menstrual weeks. Between 7–9 weeks, both the corpus luteum and
the placenta produce progesterone. After 9 weeks the corpus luteum declines,
and progesterone is exclusively produced by the placenta.