The foetus is nourished by:

Following changes can be seen in the first trimester of pregnancy,$EXCEPT$:

The number of foetal membranes in humans is

The presence of $HCG$ in the urine of a woman indicates what?

$A$: If fertilization occurs,the corpus luteum is rescued from regression by human chorionic gonadotropin $(hCG)$,which is produced by the placenta.
$R$: In the first trimester,the corpus luteum,stimulated by $hCG$,is responsible for the production of progesterone.

The persistence of corpus luteum during pregnancy is due to a hormone known as