Hi Doctor. I Am 30 Years Old, 16 Weeks Pregnant

Hi doctor. I am 30 years old, 16 weeks pregnant with my second child and have no history of miscarriages. This week my doctor has prescribed me to take utrogestan capsules(natural progesterone) orally. But its leaflet says " Utrogestan should only be used in pregnancy during the first trimester and only by the vaginal route. There are some risks of undesirable effects on the liver during the second and third trimesters of pregnancy. " should I still take it? Whats the logic behind prescribing utrogestan in second trimester?
Also, she advised to take loprin daily as a precautionary measure to avoid oligohydramnios(which I faced in last trimester of my first pregnancy). Is it necessary and safe to start loprin as a precaution?