During pregnancy, leaving urine sample at every Dr's visit

Everytime you are visiting the doctor, why are you asked to leave your urine sample?

Many of us must be wondering what do they test for. Here's the reason. The urine is
tested for mainly protein and sugar levels. Also, they would check for other infections. Based on protein levels, doctor can tell whether you are affected with Pre-eclampsia which can develop from 20weeks. After 32 weeksn it's not considered critical but before that it's considered to be dangerous and precautions have to be followed. This is the most common of the dangerous pregnancy complications.