Welcome to HCM.
Duphaston is a progesterone
tablet and is given in some progesterone deficient disorder.It also protects early pregnancy loss or miscarriage
.So it is advised generally to take up to 16 wk if there is something problem in pregnancy or history of miscarriage or other things.
After that,placenta produces natural progesterone to continue and support journey of pregnancy. So no need to take extra progesterone tab and it may give ill-health effect to fetus.
It is better to avoid unnecessary medication or hormonal tablet in pregnancy.
If cyst in the left ovary is small,then no need to worry much.Just do periodic check up.
If there is large ovarian cyst
,then it needs intervention and ovarian cystectomy
is to be done during caesarean section
Consult with your doctor and take advice.Also do a USG scan in 3rd trimester to assess the overall pregnancy status.