What maintains the integrity of the uterine lining during the first trimester?

Question

The actual question from the study focus reads: Estrogen and progesterone maintain the integrity of the uterine lining and help produce milk. What structure is responsible for this during the first 3 months of pregnancy?

Can't be estrogen or progesterone.

Answer 1

Not HCG -

After the egg has been fertilised,  it becomes embedded in the wall of the uterus, (see article on becoming pregnant).  This implantation takes place about 8 days after the impregnation.  This action has the effect of releasing the hormone ß-hCG.  It is this hormone that is tested for in home pregnancy tests.

ß-HCG encourages the "yellow body" (corpus luteum) to produce progesterone and estrogen during the early stages of the pregnancy.  This situation remains the same for the first trimester of pregnancy, the placenta will eventually replace the function of the "yellow body" by producing its own progesterone, thus the levels of ß-HCG will drop back quickly in the second trimester to between 10 percent and 30 percent of the peak levels.

Try Progesterone.  The ovaries continue to produce progesterone (and estrogen) during the first 8 to 9 weeks until the placenta begins to reduce the amount of b-HCG secreted, which is a signal to the "yellow body" that it is capable of producing these hormones for itself and requires less help

Answer 2

Human chorionic gonadotrophin (hCG)

Answer 3

Yeah, what Pete said.