I'm just over 17 weeks and have noticed that my pee is a lil bit brighter yellow. I just saw my doctor today and he said everything looked good and the baby's heartbeat was good. So I don't think there is any cause for concern because on most prenatal vitamins it says they may change the color of your urine.
Yellow urine means you're dehydrated. Urine should be clear.
If ur taking vitamins it makes your pee highlighter color ! Mines always bright yellow. Ps im always hydrated drink about 15 bottle of water a day